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Copyright (c) 2009 Sun Microsystems, Inc. All Rights Reserved.
Copyright 2011 Joshua M. Clulow <josh@sysmgr.org>
Copyright (c) 2011, 2015 by Delphix. All rights reserved.
Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
Copyright (c) 2014, Joyent, Inc. All rights reserved.
Copyright (c) 2014 by Adam Stevko. All rights reserved.
Copyright (c) 2014 Integros [integros.com]
Copyright 2016 Nexenta Systems, Inc.

.Dd March 20, 2016 .Dt ZFS 1M .Os .Sh NAME .Nm zfs .Nd configures ZFS file systems .Sh SYNOPSIS .Nm .Op Fl \? .Nm .Cm create .Op Fl p .Oo Fl o Ar property Ns = Ns Ar value Oc Ns ... .Ar filesystem .Nm .Cm create .Op Fl ps .Op Fl b Ar blocksize .Oo Fl o Ar property Ns = Ns Ar value Oc Ns ... .Fl V Ar size Ar volume .Nm .Cm destroy .Op Fl Rfnprv .Ar filesystem Ns | Ns Ar volume .Nm .Cm destroy .Op Fl Rdnprv .Ar filesystem Ns | Ns Ar volume Ns @ Ns Ar snap Ns .Oo % Ns Ar snap Ns Oo , Ns Ar snap Ns Oo % Ns Ar snap Oc Oc Oc Ns ... .Nm .Cm destroy .Ar filesystem Ns | Ns Ar volume Ns # Ns Ar bookmark .Nm .Cm snapshot .Op Fl r .Oo Fl o Ar property Ns = Ns value Oc Ns ... .Ar filesystem Ns @ Ns Ar snapname Ns | Ns Ar volume Ns @ Ns Ar snapname Ns ... .Nm .Cm rollback .Op Fl Rfr .Ar snapshot .Nm .Cm clone .Op Fl p .Oo Fl o Ar property Ns = Ns Ar value Oc Ns ... .Ar snapshot Ar filesystem Ns | Ns Ar volume .Nm .Cm promote .Ar clone-filesystem .Nm .Cm rename .Op Fl f .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot .Nm .Cm rename .Op Fl fp .Ar filesystem Ns | Ns Ar volume .Ar filesystem Ns | Ns Ar volume .Nm .Cm rename .Fl r .Ar snapshot Ar snapshot .Nm .Cm list .Op Fl r Ns | Ns Fl d Ar depth .Op Fl Hp .Oo Fl o Ar property Ns Oo , Ns Ar property Oc Ns ... Oc .Oo Fl s Ar property Oc Ns ... .Oo Fl S Ar property Oc Ns ... .Oo Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Oc .Oo Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Oc Ns ... .Nm .Cm set .Ar property Ns = Ns Ar value Oo Ar property Ns = Ns Ar value Oc Ns ... .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Ns ... .Nm .Cm get .Op Fl r Ns | Ns Fl d Ar depth .Op Fl Hp .Oo Fl o Ar field Ns Oo , Ns Ar field Oc Ns ... Oc .Oo Fl s Ar source Ns Oo , Ns Ar source Oc Ns ... Oc .Oo Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Oc .Cm all | Ar property Ns Oo , Ns Ar property Oc Ns ... .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Ns ... .Nm .Cm inherit .Op Fl rS .Ar property Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Ns ... .Nm .Cm upgrade .Nm .Cm upgrade .Fl v .Nm .Cm upgrade .Op Fl r .Op Fl V Ar version .Fl a | Ar filesystem .Nm .Cm userspace .Op Fl Hinp .Oo Fl o Ar field Ns Oo , Ns Ar field Oc Ns ... Oc .Oo Fl s Ar field Oc Ns ... .Oo Fl S Ar field Oc Ns ... .Oo Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Oc .Ar filesystem Ns | Ns Ar snapshot .Nm .Cm groupspace .Op Fl Hinp .Oo Fl o Ar field Ns Oo , Ns Ar field Oc Ns ... Oc .Oo Fl s Ar field Oc Ns ... .Oo Fl S Ar field Oc Ns ... .Oo Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Oc .Ar filesystem Ns | Ns Ar snapshot .Nm .Cm mount .Nm .Cm mount .Op Fl Ov .Op Fl o Ar options .Fl a | Ar filesystem .Nm .Cm unmount .Op Fl f .Fl a | Ar filesystem Ns | Ns Ar mountpoint .Nm .Cm share .Fl a | Ar filesystem .Nm .Cm unshare .Fl a | Ar filesystem Ns | Ns Ar mountpoint .Nm .Cm bookmark .Ar snapshot bookmark .Nm .Cm send .Op Fl DLPRenpv .Op Oo Fl I Ns | Ns Fl i Oc Ar snapshot .Ar snapshot .Nm .Cm send .Op Fl Le .Op Fl i Ar snapshot Ns | Ns Ar bookmark .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot .Nm .Cm send .Op Fl Penv .Fl t Ar receive_resume_token .Nm .Cm receive .Op Fl Fnsuv .Op Fl o Sy origin Ns = Ns Ar snapshot .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot .Nm .Cm receive .Op Fl Fnsuv .Op Fl d Ns | Ns Fl e .Op Fl o Sy origin Ns = Ns Ar snapshot .Ar filesystem .Nm .Cm receive .Fl A .Ar filesystem Ns | Ns Ar volume .Nm .Cm allow .Ar filesystem Ns | Ns Ar volume .Nm .Cm allow .Op Fl dglu .Ar user Ns | Ns Ar group Ns Oo , Ns Ar user Ns | Ns Ar group Oc Ns ... .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Ar filesystem Ns | Ns Ar volume .Nm .Cm allow .Op Fl dl .Fl e Ns | Ns Sy everyone .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Ar filesystem Ns | Ns Ar volume .Nm .Cm allow .Fl c .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Ar filesystem Ns | Ns Ar volume .Nm .Cm allow .Fl s No @ Ns Ar setname .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Ar filesystem Ns | Ns Ar volume .Nm .Cm unallow .Op Fl dglru .Ar user Ns | Ns Ar group Ns Oo , Ns Ar user Ns | Ns Ar group Oc Ns ... .Oo Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... Oc .Ar filesystem Ns | Ns Ar volume .Nm .Cm unallow .Op Fl dlr .Fl e Ns | Ns Sy everyone .Oo Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... Oc .Ar filesystem Ns | Ns Ar volume .Nm .Cm unallow .Op Fl r .Fl c .Oo Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... Oc .Ar filesystem Ns | Ns Ar volume .Nm .Cm unallow .Op Fl r .Fl s @ Ns Ar setname .Oo Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... Oc .Ar filesystem Ns | Ns Ar volume .Nm .Cm hold .Op Fl r .Ar tag Ar snapshot Ns ... .Nm .Cm holds .Op Fl r .Ar snapshot Ns ... .Nm .Cm release .Op Fl r .Ar tag Ar snapshot Ns ... .Nm .Cm diff .Op Fl FHt .Ar snapshot Ar snapshot Ns | Ns Ar filesystem .Sh DESCRIPTION The .Nm command configures ZFS datasets within a ZFS storage pool, as described in .Xr zpool 1M . A dataset is identified by a unique path within the ZFS namespace. For example: d -literal pool/{filesystem,volume,snapshot} .Ed

p where the maximum length of a dataset name is .Dv MAXNAMELEN

q 256 bytes .

p A dataset can be one of the following: l -tag -width "file system" t Sy file system A ZFS dataset of type .Sy filesystem can be mounted within the standard system namespace and behaves like other file systems. While ZFS file systems are designed to be POSIX compliant, known issues exist that prevent compliance in some cases. Applications that depend on standards conformance might fail due to non-standard behavior when checking file system free space. t Sy volume A logical volume exported as a raw or block device. This type of dataset should only be used under special circumstances. File systems are typically used in most environments. t Sy snapshot A read-only version of a file system or volume at a given point in time. It is specified as .Ar filesystem Ns @ Ns Ar name or .Ar volume Ns @ Ns Ar name . .El .Ss ZFS File System Hierarchy A ZFS storage pool is a logical collection of devices that provide space for datasets. A storage pool is also the root of the ZFS file system hierarchy.

p The root of the pool can be accessed as a file system, such as mounting and unmounting, taking snapshots, and setting properties. The physical storage characteristics, however, are managed by the .Xr zpool 1M command.

p See .Xr zpool 1M for more information on creating and administering pools. .Ss Snapshots A snapshot is a read-only copy of a file system or volume. Snapshots can be created extremely quickly, and initially consume no additional space within the pool. As data within the active dataset changes, the snapshot consumes more data than would otherwise be shared with the active dataset.

p Snapshots can have arbitrary names. Snapshots of volumes can be cloned or rolled back, but cannot be accessed independently.

p File system snapshots can be accessed under the

a .zfs/snapshot directory in the root of the file system. Snapshots are automatically mounted on demand and may be unmounted at regular intervals. The visibility of the

a .zfs directory can be controlled by the snapdir property. .Ss Clones A clone is a writable volume or file system whose initial contents are the same as another dataset. As with snapshots, creating a clone is nearly instantaneous, and initially consumes no additional space.

p Clones can only be created from a snapshot. When a snapshot is cloned, it creates an implicit dependency between the parent and child. Even though the clone is created somewhere else in the dataset hierarchy, the original snapshot cannot be destroyed as long as a clone exists. The .Sy origin property exposes this dependency, and the .Cm destroy command lists any such dependencies, if they exist.

p The clone parent-child dependency relationship can be reversed by using the .Cm promote subcommand. This causes the .Qq origin file system to become a clone of the specified file system, which makes it possible to destroy the file system that the clone was created from. .Ss "Mount Points" Creating a ZFS file system is a simple operation, so the number of file systems per system is likely to be numerous. To cope with this, ZFS automatically manages mounting and unmounting file systems without the need to edit the

a /etc/vfstab file. All automatically managed file systems are mounted by ZFS at boot time.

p By default, file systems are mounted under

a /path , where .Ar path is the name of the file system in the ZFS namespace. Directories are created and destroyed as needed.

p A file system can also have a mount point set in the .Sy mountpoint property. This directory is created as needed, and ZFS automatically mounts the file system when the .Nm zfs Cm mount Fl a command is invoked

o without editing

a /etc/vfstab

c . The .Sy mountpoint property can be inherited, so if .Em pool/home has a mount point of

a /export/stuff , then .Em pool/home/user automatically inherits a mount point of

a /export/stuff/user .

p A file system .Sy mountpoint property of .Sy none prevents the file system from being mounted.

p If needed, ZFS file systems can also be managed with traditional tools

o .Nm mount , .Nm umount ,

a /etc/vfstab

c . If a file system's mount point is set to .Sy legacy , ZFS makes no attempt to manage the file system, and the administrator is responsible for mounting and unmounting the file system. .Ss "Zones" A ZFS file system can be added to a non-global zone by using the .Nm zonecfg Cm add Sy fs subcommand. A ZFS file system that is added to a non-global zone must have its .Sy mountpoint property set to .Sy legacy .

p The physical properties of an added file system are controlled by the global administrator. However, the zone administrator can create, modify, or destroy files within the added file system, depending on how the file system is mounted.

p A dataset can also be delegated to a non-global zone by using the .Nm zonecfg Cm add Sy dataset subcommand. You cannot delegate a dataset to one zone and the children of the same dataset to another zone. The zone administrator can change properties of the dataset or any of its children. However, the .Sy quota , .Sy filesystem_limit and .Sy snapshot_limit properties of the delegated dataset can be modified only by the global administrator.

p A ZFS volume can be added as a device to a non-global zone by using the .Nm zonecfg Cm add Sy device subcommand. However, its physical properties can be modified only by the global administrator.

p For more information about .Nm zonecfg syntax, see .Xr zonecfg 1M .

p After a dataset is delegated to a non-global zone, the .Sy zoned property is automatically set. A zoned file system cannot be mounted in the global zone, since the zone administrator might have to set the mount point to an unacceptable value.

p The global administrator can forcibly clear the .Sy zoned property, though this should be done with extreme care. The global administrator should verify that all the mount points are acceptable before clearing the property. .Ss Native Properties Properties are divided into two types, native properties and user-defined

o or .Qq user

c properties. Native properties either export internal statistics or control ZFS behavior. In addition, native properties are either editable or read-only. User properties have no effect on ZFS behavior, but you can use them to annotate datasets in a way that is meaningful in your environment. For more information about user properties, see the .Sx User Properties section, below.

p Every dataset has a set of properties that export statistics about the dataset as well as control various behaviors. Properties are inherited from the parent unless overridden by the child. Some properties apply only to certain types of datasets

q file systems, volumes, or snapshots .

p The values of numeric properties can be specified using human-readable suffixes

o for example, .Sy k , .Sy KB , .Sy M , .Sy Gb , and so forth, up to .Sy Z for zettabyte

c . The following are all valid

q and equal specifications: .Li 1536M, 1.5g, 1.50GB .

p The values of non-numeric properties are case sensitive and must be lowercase, except for .Sy mountpoint , .Sy sharenfs , and .Sy sharesmb .

p The following native properties consist of read-only statistics about the dataset. These properties can be neither set, nor inherited. Native properties apply to all dataset types unless otherwise noted. l -tag -width "usedbyrefreservation" t Sy available The amount of space available to the dataset and all its children, assuming that there is no other activity in the pool. Because space is shared within a pool, availability can be limited by any number of factors, including physical pool size, quotas, reservations, or other datasets within the pool.

p This property can also be referred to by its shortened column name, .Sy avail . t Sy compressratio For non-snapshots, the compression ratio achieved for the .Sy used space of this dataset, expressed as a multiplier. The .Sy used property includes descendant datasets, and, for clones, does not include the space shared with the origin snapshot. For snapshots, the .Sy compressratio is the same as the .Sy refcompressratio property. Compression can be turned on by running: .Nm zfs Cm set Sy compression Ns = Ns Sy on Ar dataset . The default value is .Sy off . t Sy creation The time this dataset was created. t Sy clones For snapshots, this property is a comma-separated list of filesystems or volumes which are clones of this snapshot. The clones' .Sy origin property is this snapshot. If the .Sy clones property is not empty, then this snapshot can not be destroyed

o even with the .Fl r or .Fl f options

c . t Sy defer_destroy This property is .Sy on if the snapshot has been marked for deferred destroy by using the .Nm zfs Cm destroy Fl d command. Otherwise, the property is .Sy off . t Sy filesystem_count The total number of filesystems and volumes that exist under this location in the dataset tree. This value is only available when a .Sy filesystem_limit has been set somewhere in the tree under which the dataset resides. t Sy logicalreferenced The amount of space that is .Qq logically accessible by this dataset. See the .Sy referenced property. The logical space ignores the effect of the .Sy compression and .Sy copies properties, giving a quantity closer to the amount of data that applications see. However, it does include space consumed by metadata.

p This property can also be referred to by its shortened column name, .Sy lrefer . t Sy logicalused The amount of space that is .Qq logically consumed by this dataset and all its descendents. See the .Sy used property. The logical space ignores the effect of the .Sy compression and .Sy copies properties, giving a quantity closer to the amount of data that applications see. However, it does include space consumed by metadata.

p This property can also be referred to by its shortened column name, .Sy lused . t Sy mounted For file systems, indicates whether the file system is currently mounted. This property can be either .Sy yes or .Sy no . t Sy origin For cloned file systems or volumes, the snapshot from which the clone was created. See also the .Sy clones property. t Sy receive_resume_token For filesystems or volumes which have saved partially-completed state from .Sy zfs receive -s , this opaque token can be provided to .Sy zfs send -t to resume and complete the .Sy zfs receive . t Sy referenced The amount of data that is accessible by this dataset, which may or may not be shared with other datasets in the pool. When a snapshot or clone is created, it initially references the same amount of space as the file system or snapshot it was created from, since its contents are identical.

p This property can also be referred to by its shortened column name, .Sy refer . t Sy refcompressratio The compression ratio achieved for the .Sy referenced space of this dataset, expressed as a multiplier. See also the .Sy compressratio property. t Sy snapshot_count The total number of snapshots that exist under this location in the dataset tree. This value is only available when a .Sy snapshot_limit has been set somewhere in the tree under which the dataset resides. t Sy type The type of dataset: .Sy filesystem , .Sy volume , or .Sy snapshot . t Sy used The amount of space consumed by this dataset and all its descendents. This is the value that is checked against this dataset's quota and reservation. The space used does not include this dataset's reservation, but does take into account the reservations of any descendent datasets. The amount of space that a dataset consumes from its parent, as well as the amount of space that are freed if this dataset is recursively destroyed, is the greater of its space used and its reservation.

p When snapshots

o see the .Sx Snapshots section

c are created, their space is initially shared between the snapshot and the file system, and possibly with previous snapshots. As the file system changes, space that was previously shared becomes unique to the snapshot, and counted in the snapshot's space used. Additionally, deleting snapshots can increase the amount of space unique to

q and used by other snapshots.

p The amount of space used, available, or referenced does not take into account pending changes. Pending changes are generally accounted for within a few seconds. Committing a change to a disk using .Xr fsync 3C or .Dv O_SYNC does not necessarily guarantee that the space usage information is updated immediately. t Sy usedby* The .Sy usedby* properties decompose the .Sy used properties into the various reasons that space is used. Specifically, .Sy used No = .Sy usedbychildren No + .Sy usedbydataset No + .Sy usedbyrefreservation No + .Sy usedbysnapshots . These properties are only available for datasets created on .Nm zpool .Qo version 13 Qc pools. t Sy usedbychildren The amount of space used by children of this dataset, which would be freed if all the dataset's children were destroyed. t Sy usedbydataset The amount of space used by this dataset itself, which would be freed if the dataset were destroyed

o after first removing any .Sy refreservation and destroying any necessary snapshots or descendents

c . t Sy usedbyrefreservation The amount of space used by a .Sy refreservation set on this dataset, which would be freed if the .Sy refreservation was removed. t Sy usedbysnapshots The amount of space consumed by snapshots of this dataset. In particular, it is the amount of space that would be freed if all of this dataset's snapshots were destroyed. Note that this is not simply the sum of the snapshots' .Sy used properties because space can be shared by multiple snapshots. t Sy userused Ns @ Ns Em user The amount of space consumed by the specified user in this dataset. Space is charged to the owner of each file, as displayed by .Nm ls Fl l . The amount of space charged is displayed by .Nm du and .Nm ls Fl s . See the .Nm zfs Cm userspace subcommand for more information.

p Unprivileged users can access only their own space usage. The root user, or a user who has been granted the .Sy userused privilege with .Nm zfs Cm allow , can access everyone's usage.

p The .Sy userused Ns @ Ns Em ... properties are not displayed by .Nm zfs Cm get Sy all . The user's name must be appended after the @ symbol, using one of the following forms: l -bullet -width "" t .Em POSIX name

o for example, .Sy joe

c t .Em POSIX numeric ID

o for example, .Sy 789

c t .Em SID name

o for example, .Sy joe.smith@mydomain

c t .Em SID numeric ID

o for example, .Sy S-1-123-456-789

c .El t Sy userrefs This property is set to the number of user holds on this snapshot. User holds are set by using the .Nm zfs Cm hold command. t Sy groupused Ns @ Ns Em group The amount of space consumed by the specified group in this dataset. Space is charged to the group of each file, as displayed by .Nm ls Fl l . See the .Sy userused Ns @ Ns Em user property for more information.

p Unprivileged users can only access their own groups' space usage. The root user, or a user who has been granted the .Sy groupused privilege with .Nm zfs Cm allow , can access all groups' usage. t Sy volblocksize Ns = Ns Em blocksize For volumes, specifies the block size of the volume. The .Sy blocksize cannot be changed once the volume has been written, so it should be set at volume creation time. The default .Sy blocksize for volumes is 8 Kbytes. Any power of 2 from 512 bytes to 128 Kbytes is valid.

p This property can also be referred to by its shortened column name, .Sy volblock . t Sy written The amount of .Sy referenced space written to this dataset since the previous snapshot. t Sy written Ns @ Ns Em snapshot The amount of .Sy referenced space written to this dataset since the specified snapshot. This is the space that is referenced by this dataset but was not referenced by the specified snapshot.

p The .Em snapshot may be specified as a short snapshot name

o just the part after the .Sy @

c , in which case it will be interpreted as a snapshot in the same filesystem as this dataset. The .Em snapshot may be a full snapshot name

o Em filesystem Ns @ Ns Em snapshot Pc , which for clones may be a snapshot in the origin's filesystem

q or the origin of the origin's filesystem, etc. .El

p The following native properties can be used to change the behavior of a ZFS dataset. l -tag -width "" t Xo .Sy aclinherit Ns = Ns Sy discard Ns | Ns Sy noallow Ns | Ns .Sy restricted Ns | Ns Sy passthrough Ns | Ns Sy passthrough-x .Xc Controls how ACEs are inherited when files and directories are created. l -tag -width "passthrough-x" t Sy discard does not inherit any ACEs. t Sy noallow only inherits inheritable ACEs that specify .Qq deny permissions. t Sy restricted default, removes the .Sy write_acl and .Sy write_owner permissions when the ACE is inherited. t Sy passthrough inherits all inheritable ACEs without any modifications. t Sy passthrough-x same meaning as .Sy passthrough , except that the .Sy owner@ , .Sy group@ , and .Sy everyone@ ACEs inherit the execute permission only if the file creation mode also requests the execute bit. .El

p When the property value is set to .Sy passthrough , files are created with a mode determined by the inheritable ACEs. If no inheritable ACEs exist that affect the mode, then the mode is set in accordance to the requested mode from the application. t Xo .Sy aclmode Ns = Ns Sy discard Ns | Ns Sy groupmask Ns | Ns .Sy passthrough Ns | Ns Sy restricted .Xc Controls how an ACL is modified during .Xr chmod 2 and how inherited ACEs are modified by the file creation mode. l -tag -width "passthrough" t Sy discard default, deletes all ACEs except for those representing the mode of the file or directory requested by .Xr chmod 2 . t Sy groupmask reduces permissions granted by all .Sy ALLOW entries found in the ACL such that they are no greater than the group permissions specified by the mode. t Sy passthrough indicates that no changes are made to the ACL other than creating or updating the necessary ACEs to represent the new mode of the file or directory. t Sy restricted causes the .Xr chmod 2 operation to return an error when used on any file or directory which has a non-trivial ACL, with entries in addition to those that represent the mode. .El

p .Xr chmod 2 is required to change the set user ID, set group ID, or sticky bit on a file or directory, as they do not have equivalent ACEs. In order to use .Xr chmod 2 on a file or directory with a non-trivial ACL when .Sy aclmode is set to .Sy restricted , you must first remove all ACEs except for those that represent the current mode. t Sy atime Ns = Ns Sy on Ns | Ns Sy off Controls whether the access time for files is updated when they are read. Turning this property off avoids producing write traffic when reading files and can result in significant performance gains, though it might confuse mailers and other similar utilities. The default value is .Sy on . t Sy canmount Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Sy noauto If this property is set to .Sy off , the file system cannot be mounted, and is ignored by .Nm zfs Cm mount Fl a . Setting this property to .Sy off is similar to setting the .Sy mountpoint property to .Sy none , except that the dataset still has a normal .Sy mountpoint property, which can be inherited. Setting this property to .Sy off allows datasets to be used solely as a mechanism to inherit properties. One example of setting .Sy canmount Ns = Ns Sy off is to have two datasets with the same .Sy mountpoint , so that the children of both datasets appear in the same directory, but might have different inherited characteristics.

p When set to .Sy noauto , a dataset can only be mounted and unmounted explicitly. The dataset is not mounted automatically when the dataset is created or imported, nor is it mounted by the .Nm zfs Cm mount Fl a command or unmounted by the .Nm zfs Cm unmount Fl a command.

p This property is not inherited. t Xo .Sy checksum Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Sy fletcher2 Ns | Ns .Sy fletcher4 Ns | Ns Sy sha256 Ns | Ns Sy noparity Ns | Ns .Sy sha512 Ns | Ns Sy skein Ns | Ns Sy edonr .Xc Controls the checksum used to verify data integrity. The default value is .Sy on , which automatically selects an appropriate algorithm

o currently, .Sy fletcher4 , but this may change in future releases

c . The value .Sy off disables integrity checking on user data. The value .Sy noparity not only disables integrity but also disables maintaining parity for user data. This setting is used internally by a dump device residing on a RAID-Z pool and should not be used by any other dataset. Disabling checksums is .Sy NOT a recommended practice.

p The .Sy sha512 , .Sy skein , and .Sy edonr checksum algorithms require enabling the appropriate features on the pool. Please see .Xr zpool-features 5 for more information on these algorithms.

p Changing this property affects only newly-written data. t Xo .Sy compression Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Sy gzip Ns | Ns .Sy gzip- Ns Em N Ns | Ns Sy lz4 Ns | Ns Sy lzjb Ns | Ns Sy zle .Xc Controls the compression algorithm used for this dataset.

p Setting compression to .Sy on indicates that the current default compression algorithm should be used. The default balances compression and decompression speed, with compression ratio and is expected to work well on a wide variety of workloads. Unlike all other settings for this property, .Sy on does not select a fixed compression type. As new compression algorithms are added to ZFS and enabled on a pool, the default compression algorithm may change. The current default compression algorthm is either .Sy lzjb or, if the .Sy lz4_compress feature is enabled, .Sy lz4 .

p The .Sy lz4 compression algorithm is a high-performance replacement for the .Sy lzjb algorithm. It features significantly faster compression and decompression, as well as a moderately higher compression ratio than .Sy lzjb , but can only be used on pools with the .Sy lz4_compress feature set to .Sy enabled . See .Xr zpool-features 5 for details on ZFS feature flags and the .Sy lz4_compress feature.

p The .Sy lzjb compression algorithm is optimized for performance while providing decent data compression.

p The .Sy gzip compression algorithm uses the same compression as the .Xr gzip 1 command. You can specify the .Sy gzip level by using the value .Sy gzip- Ns Em N , where .Em N is an integer from 1

q fastest to 9

q best compression ratio . Currently, .Sy gzip is equivalent to .Sy gzip-6

o which is also the default for .Xr gzip 1

c .

p The .Sy zle compression algorithm compresses runs of zeros.

p This property can also be referred to by its shortened column name compress. Changing this property affects only newly-written data. t Sy copies Ns = Ns Sy 1 Ns | Ns Sy 2 Ns | Ns Sy 3 Controls the number of copies of data stored for this dataset. These copies are in addition to any redundancy provided by the pool, for example, mirroring or RAID-Z. The copies are stored on different disks, if possible. The space used by multiple copies is charged to the associated file and dataset, changing the .Sy used property and counting against quotas and reservations.

p Changing this property only affects newly-written data. Therefore, set this property at file system creation time by using the .Fl o Sy copies Ns = Ns Ar N option. t Sy devices Ns = Ns Sy on Ns | Ns Sy off Controls whether device nodes can be opened on this file system. The default value is .Sy on . t Sy exec Ns = Ns Sy on Ns | Ns Sy off Controls whether processes can be executed from within this file system. The default value is .Sy on . t Sy filesystem_limit Ns = Ns Em count Ns | Ns Sy none Limits the number of filesystems and volumes that can exist under this point in the dataset tree. The limit is not enforced if the user is allowed to change the limit. Setting a .Sy filesystem_limit to .Sy on a descendent of a filesystem that already has a .Sy filesystem_limit does not override the ancestor's .Sy filesystem_limit , but rather imposes an additional limit. This feature must be enabled to be used

o see .Xr zpool-features 5

c . t Sy mountpoint Ns = Ns Pa path Ns | Ns Sy none Ns | Ns Sy legacy Controls the mount point used for this file system. See the .Sx Mount Points section for more information on how this property is used.

p When the .Sy mountpoint property is changed for a file system, the file system and any children that inherit the mount point are unmounted. If the new value is .Sy legacy , then they remain unmounted. Otherwise, they are automatically remounted in the new location if the property was previously .Sy legacy or .Sy none , or if they were mounted before the property was changed. In addition, any shared file systems are unshared and shared in the new location. t Sy nbmand Ns = Ns Sy on Ns | Ns Sy off Controls whether the file system should be mounted with .Sy nbmand

q Non Blocking mandatory locks . This is used for SMB clients. Changes to this property only take effect when the file system is umounted and remounted. See .Xr mount 1M for more information on .Sy nbmand mounts. t Sy primarycache Ns = Ns Sy all Ns | Ns Sy none Ns | Ns Sy metadata Controls what is cached in the primary cache

q ARC . If this property is set to .Sy all , then both user data and metadata is cached. If this property is set to .Sy none , then neither user data nor metadata is cached. If this property is set to .Sy metadata , then only metadata is cached. The default value is .Sy all . t Sy quota Ns = Ns Em size Ns | Ns Sy none Limits the amount of space a dataset and its descendents can consume. This property enforces a hard limit on the amount of space used. This includes all space consumed by descendents, including file systems and snapshots. Setting a quota on a descendent of a dataset that already has a quota does not override the ancestor's quota, but rather imposes an additional limit.

p Quotas cannot be set on volumes, as the .Sy volsize property acts as an implicit quota. t Sy snapshot_limit Ns = Ns Em count Ns | Ns Sy none Limits the number of snapshots that can be created on a dataset and its descendents. Setting a .Sy snapshot_limit on a descendent of a dataset that already has a .Sy snapshot_limit does not override the ancestor's .Sy snapshot_limit , but rather imposes an additional limit. The limit is not enforced if the user is allowed to change the limit. For example, this means that recursive snapshots taken from the global zone are counted against each delegated dataset within a zone. This feature must be enabled to be used

o see .Xr zpool-features 5

c . t Sy userquota@ Ns Em user Ns = Ns Em size Ns | Ns Sy none Limits the amount of space consumed by the specified user. User space consumption is identified by the .Sy userspace@ Ns Em user property.

p Enforcement of user quotas may be delayed by several seconds. This delay means that a user might exceed their quota before the system notices that they are over quota and begins to refuse additional writes with the .Er EDQUOT error message. See the .Nm zfs Cm userspace subcommand for more information.

p Unprivileged users can only access their own groups' space usage. The root user, or a user who has been granted the .Sy userquota privilege with .Nm zfs Cm allow , can get and set everyone's quota.

p This property is not available on volumes, on file systems before version 4, or on pools before version 15. The .Sy userquota@ Ns Em ... properties are not displayed by .Nm zfs Cm get Sy all . The user's name must be appended after the .Sy @ symbol, using one of the following forms: l -bullet t .Em POSIX name

o for example, .Sy joe

c t .Em POSIX numeric ID

o for example, .Sy 789

c t .Em SID name

o for example, .Sy joe.smith@mydomain

c t .Em SID numeric ID

o for example, .Sy S-1-123-456-789

c .El t Sy groupquota@ Ns Em group Ns = Ns Em size Ns | Ns Sy none Limits the amount of space consumed by the specified group. Group space consumption is identified by the .Sy groupused@ Ns Em group property.

p Unprivileged users can access only their own groups' space usage. The root user, or a user who has been granted the .Sy groupquota privilege with .Nm zfs Cm allow , can get and set all groups' quotas. t Sy readonly Ns = Ns Sy on Ns | Ns Sy off Controls whether this dataset can be modified. The default value is .Sy off .

p This property can also be referred to by its shortened column name, .Sy rdonly . t Sy recordsize Ns = Ns Em size Specifies a suggested block size for files in the file system. This property is designed solely for use with database workloads that access files in fixed-size records. ZFS automatically tunes block sizes according to internal algorithms optimized for typical access patterns.

p For databases that create very large files but access them in small random chunks, these algorithms may be suboptimal. Specifying a .Sy recordsize greater than or equal to the record size of the database can result in significant performance gains. Use of this property for general purpose file systems is strongly discouraged, and may adversely affect performance.

p The size specified must be a power of two greater than or equal to 512 and less than or equal to 128 Kbytes. If the .Sy large_blocks feature is enabled on the pool, the size may be up to 1 Mbyte. See .Xr zpool-features 5 for details on ZFS feature flags.

p Changing the file system's .Sy recordsize affects only files created afterward; existing files are unaffected.

p This property can also be referred to by its shortened column name, .Sy recsize . t Sy redundant_metadata Ns = Ns Sy all Ns | Ns Sy most Controls what types of metadata are stored redundantly. ZFS stores an extra copy of metadata, so that if a single block is corrupted, the amount of user data lost is limited. This extra copy is in addition to any redundancy provided at the pool level

q e.g. by mirroring or RAID-Z , and is in addition to an extra copy specified by the .Sy copies property

q up to a total of 3 copies . For example if the pool is mirrored, .Sy copies Ns = Ns 2 , and .Sy redundant_metadata Ns = Ns Sy most , then ZFS stores 6 copies of most metadata, and 4 copies of data and some metadata.

p When set to .Sy all , ZFS stores an extra copy of all metadata. If a single on-disk block is corrupt, at worst a single block of user data

o which is .Sy recordsize bytes long

c can be lost.

p When set to .Sy most , ZFS stores an extra copy of most types of metadata. This can improve performance of random writes, because less metadata must be written. In practice, at worst about 100 blocks

o of .Sy recordsize bytes each

c of user data can be lost if a single on-disk block is corrupt. The exact behavior of which metadata blocks are stored redundantly may change in future releases.

p The default value is .Sy all . t Sy refquota Ns = Ns Em size Ns | Ns Sy none Limits the amount of space a dataset can consume. This property enforces a hard limit on the amount of space used. This hard limit does not include space used by descendents, including file systems and snapshots. t Sy refreservation Ns = Ns Em size Ns | Ns Sy none The minimum amount of space guaranteed to a dataset, not including its descendents. When the amount of space used is below this value, the dataset is treated as if it were taking up the amount of space specified by .Sy refreservation . The .Sy refreservation reservation is accounted for in the parent datasets' space used, and counts against the parent datasets' quotas and reservations.

p If .Sy refreservation is set, a snapshot is only allowed if there is enough free pool space outside of this reservation to accommodate the current number of .Qq referenced bytes in the dataset.

p This property can also be referred to by its shortened column name, .Sy refreserv . t Sy reservation Ns = Ns Em size Ns | Ns Sy none The minimum amount of space guaranteed to a dataset and its descendents. When the amount of space used is below this value, the dataset is treated as if it were taking up the amount of space specified by its reservation. Reservations are accounted for in the parent datasets' space used, and count against the parent datasets' quotas and reservations.

p This property can also be referred to by its shortened column name, .Sy reserv . t Sy secondarycache Ns = Ns Sy all Ns | Ns Sy none Ns | Ns Sy metadata Controls what is cached in the secondary cache

q L2ARC . If this property is set to .Sy all , then both user data and metadata is cached. If this property is set to .Sy none , then neither user data nor metadata is cached. If this property is set to .Sy metadata , then only metadata is cached. The default value is .Sy all . t Sy setuid Ns = Ns Sy on Ns | Ns Sy off Controls whether the setuid bit is respected for the file system. The default value is .Sy on . t Sy sharesmb Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Em opts Controls whether the file system is shared via SMB, and what options are to be used. A file system with the .Sy sharesmb property set to .Sy off is managed through traditional tools such as .Xr sharemgr 1M . Otherwise, the file system is automatically shared and unshared with the .Nm zfs Cm share and .Nm zfs Cm unshare commands. If the property is set to .Sy on , the .Xr sharemgr 1M command is invoked with no options. Otherwise, the .Xr sharemgr 1M command is invoked with options equivalent to the contents of this property.

p Because SMB shares requires a resource name, a unique resource name is constructed from the dataset name. The constructed name is a copy of the dataset name except that the characters in the dataset name, which would be illegal in the resource name, are replaced with underscore

q Sy _ characters. A pseudo property .Qq name is also supported that allows you to replace the data set name with a specified name. The specified name is then used to replace the prefix dataset in the case of inheritance. For example, if the dataset .Em data/home/john is set to .Sy name Ns = Ns Sy john , then .Em data/home/john has a resource name of .Sy john . If a child dataset .Em data/home/john/backups is shared, it has a resource name of .Sy john_backups .

p When SMB shares are created, the SMB share name appears as an entry in the

a .zfs/shares directory. You can use the .Nm ls or .Nm chmod command to display the share-level ACLs on the entries in this directory.

p When the .Sy sharesmb property is changed for a dataset, the dataset and any children inheriting the property are re-shared with the new options, only if the property was previously set to .Sy off , or if they were shared before the property was changed. If the new property is set to .Sy off , the file systems are unshared. t Sy sharenfs Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Em opts Controls whether the file system is shared via NFS, and what options are to be used. A file system with a .Sy sharenfs property of .Sy off is managed through traditional tools such as .Xr share 1M , .Xr unshare 1M , and .Xr dfstab 4 . Otherwise, the file system is automatically shared and unshared with the .Nm zfs Cm share and .Nm zfs Cm unshare commands. If the property is set to .Sy on , .Xr share 1M command is invoked with no options. Otherwise, the .Xr share 1M command is invoked with options equivalent to the contents of this property.

p When the .Sy sharenfs property is changed for a dataset, the dataset and any children inheriting the property are re-shared with the new options, only if the property was previously .Sy off , or if they were shared before the property was changed. If the new property is .Sy off , the file systems are unshared. t Sy logbias Ns = Ns Sy latency Ns | Ns Sy throughput Provide a hint to ZFS about handling of synchronous requests in this dataset. If .Sy logbias is set to .Sy latency

q the default , ZFS will use pool log devices

q if configured to handle the requests at low latency. If .Sy logbias is set to .Sy throughput , ZFS will not use configured pool log devices. ZFS will instead optimize synchronous operations for global pool throughput and efficient use of resources. t Sy snapdir Ns = Ns Sy hidden Ns | Ns Sy visible Controls whether the

a .zfs directory is hidden or visible in the root of the file system as discussed in the .Sx Snapshots section. The default value is .Sy hidden . t Sy sync Ns = Ns Sy standard Ns | Ns Sy always Ns | Ns Sy disabled Controls the behavior of synchronous requests

q e.g. fsync, O_DSYNC . .Sy standard is the .Tn POSIX specified behavior of ensuring all synchronous requests are written to stable storage and all devices are flushed to ensure data is not cached by device controllers

q this is the default . .Sy always causes every file system transaction to be written and flushed before its system call returns. This has a large performance penalty. .Sy disabled disables synchronous requests. File system transactions are only committed to stable storage periodically. This option will give the highest performance. However, it is very dangerous as ZFS would be ignoring the synchronous transaction demands of applications such as databases or NFS. Administrators should only use this option when the risks are understood. t Sy version Ns = Ns Em N Ns | Ns Sy current The on-disk version of this file system, which is independent of the pool version. This property can only be set to later supported versions. See the .Nm zfs Cm upgrade command. t Sy volsize Ns = Ns Em size For volumes, specifies the logical size of the volume. By default, creating a volume establishes a reservation of equal size. For storage pools with a version number of 9 or higher, a .Sy refreservation is set instead. Any changes to .Sy volsize are reflected in an equivalent change to the reservation

o or .Sy refreservation

c . The .Sy volsize can only be set to a multiple of .Sy volblocksize , and cannot be zero.

p The reservation is kept equal to the volume's logical size to prevent unexpected behavior for consumers. Without the reservation, the volume could run out of space, resulting in undefined behavior or data corruption, depending on how the volume is used. These effects can also occur when the volume size is changed while it is in use

q particularly when shrinking the size . Extreme care should be used when adjusting the volume size.

p Though not recommended, a .Qq sparse volume

o also known as .Qq thin provisioning

c can be created by specifying the .Fl s option to the .Nm zfs Cm create Fl V command, or by changing the reservation after the volume has been created. A .Qq sparse volume is a volume where the reservation is less then the volume size. Consequently, writes to a sparse volume can fail with .Er ENOSPC when the pool is low on space. For a sparse volume, changes to .Sy volsize are not reflected in the reservation. t Sy vscan Ns = Ns Sy on Ns | Ns Sy off Controls whether regular files should be scanned for viruses when a file is opened and closed. In addition to enabling this property, the virus scan service must also be enabled for virus scanning to occur. The default value is .Sy off . t Sy xattr Ns = Ns Sy on Ns | Ns Sy off Controls whether extended attributes are enabled for this file system. The default value is .Sy on . t Sy zoned Ns = Ns Sy on Ns | Ns Sy off Controls whether the dataset is managed from a non-global zone. See the .Sx Zones section for more information. The default value is .Sy off . .El

p The following three properties cannot be changed after the file system is created, and therefore, should be set when the file system is created. If the properties are not set with the .Nm zfs Cm create or .Nm zpool Cm create commands, these properties are inherited from the parent dataset. If the parent dataset lacks these properties due to having been created prior to these features being supported, the new file system will have the default values for these properties. l -tag -width "" t Xo .Sy casesensitivity Ns = Ns Sy sensitive Ns | Ns .Sy insensitive Ns | Ns Sy mixed .Xc Indicates whether the file name matching algorithm used by the file system should be case-sensitive, case-insensitive, or allow a combination of both styles of matching. The default value for the .Sy casesensitivity property is .Sy sensitive . Traditionally, x and .Tn POSIX file systems have case-sensitive file names.

p The .Sy mixed value for the .Sy casesensitivity property indicates that the file system can support requests for both case-sensitive and case-insensitive matching behavior. Currently, case-insensitive matching behavior on a file system that supports mixed behavior is limited to the SMB server product. For more information about the .Sy mixed value behavior, see the "ZFS Administration Guide". t Xo .Sy normalization Ns = Ns Sy none Ns | Ns Sy formC Ns | Ns .Sy formD Ns | Ns Sy formKC Ns | Ns Sy formKD .Xc Indicates whether the file system should perform a .Sy unicode normalization of file names whenever two file names are compared, and which normalization algorithm should be used. File names are always stored unmodified, names are normalized as part of any comparison process. If this property is set to a legal value other than .Sy none , and the .Sy utf8only property was left unspecified, the .Sy utf8only property is automatically set to .Sy on . The default value of the .Sy normalization property is .Sy none . This property cannot be changed after the file system is created. t Sy utf8only Ns = Ns Sy on Ns | Ns Sy off Indicates whether the file system should reject file names that include characters that are not present in the .Sy UTF-8 character code set. If this property is explicitly set to .Sy off , the normalization property must either not be explicitly set or be set to .Sy none . The default value for the .Sy utf8only property is .Sy off . This property cannot be changed after the file system is created. .El

p The .Sy casesensitivity , .Sy normalization , and .Sy utf8only properties are also new permissions that can be assigned to non-privileged users by using the ZFS delegated administration feature. .Ss "Temporary Mount Point Properties" When a file system is mounted, either through .Xr mount 1M for legacy mounts or the .Nm zfs Cm mount command for normal file systems, its mount options are set according to its properties. The correlation between properties and mount options is as follows: d -literal PROPERTY MOUNT OPTION devices devices/nodevices exec exec/noexec readonly ro/rw setuid setuid/nosetuid xattr xattr/noxattr .Ed

p In addition, these options can be set on a per-mount basis using the .Fl o option, without affecting the property that is stored on disk. The values specified on the command line override the values stored in the dataset. The .Sy nosuid option is an alias for .Sy nodevices Ns , Ns Sy nosetuid . These properties are reported as .Qq temporary by the .Nm zfs Cm get command. If the properties are changed while the dataset is mounted, the new setting overrides any temporary settings. .Ss "User Properties" In addition to the standard native properties, ZFS supports arbitrary user properties. User properties have no effect on ZFS behavior, but applications or administrators can use them to annotate datasets

q file systems, volumes, and snapshots .

p User property names must contain a colon

q Qq Sy : character to distinguish them from native properties. They may contain lowercase letters, numbers, and the following punctuation characters: colon

q Qq Sy : , dash

q Qq Sy - , period

q Qq Sy . , and underscore

q Qq Sy _ . The expected convention is that the property name is divided into two portions such as .Em module Ns : Ns Em property , but this namespace is not enforced by ZFS. User property names can be at most 256 characters, and cannot begin with a dash

q Qq Sy - .

p When making programmatic use of user properties, it is strongly suggested to use a reversed .Sy DNS domain name for the .Em module component of property names to reduce the chance that two independently-developed packages use the same property name for different purposes.

p The values of user properties are arbitrary strings, are always inherited, and are never validated. All of the commands that operate on properties

o Nm zfs Cm list , .Nm zfs Cm get , .Nm zfs Cm set , and so forth

c can be used to manipulate both native properties and user properties. Use the .Nm zfs Cm inherit command to clear a user property . If the property is not defined in any parent dataset, it is removed entirely. Property values are limited to 1024 characters. .Ss ZFS Volumes as Swap or Dump Devices During an initial installation a swap device and dump device are created on ZFS volumes in the ZFS root pool. By default, the swap area size is based on 1/2 the size of physical memory up to 2 Gbytes. The size of the dump device depends on the kernel's requirements at installation time. Separate ZFS volumes must be used for the swap area and dump devices. Do not swap to a file on a ZFS file system. A ZFS swap file configuration is not supported.

p If you need to change your swap area or dump device after the system is installed or upgraded, use the .Xr swap 1M and .Xr dumpadm 1M commands. .Sh SUBCOMMANDS All subcommands that modify state are logged persistently to the pool in their original form. l -tag -width "" t Nm Fl \? Displays a help message. t Xo .Nm .Cm create .Op Fl p .Oo Fl o Ar property Ns = Ns Ar value Oc Ns ... .Ar filesystem .Xc Creates a new ZFS file system. The file system is automatically mounted according to the .Sy mountpoint property inherited from the parent. l -tag -width "-o" t Fl o Ar property Ns = Ns Ar value Sets the specified property as if the command .Nm zfs Cm set Ar property Ns = Ns Ar value was invoked at the same time the dataset was created. Any editable ZFS property can also be set at creation time. Multiple .Fl o options can be specified. An error results if the same property is specified in multiple .Fl o options. t Fl p Creates all the non-existing parent datasets. Datasets created in this manner are automatically mounted according to the .Sy mountpoint property inherited from their parent. Any property specified on the command line using the .Fl o option is ignored. If the target filesystem already exists, the operation completes successfully. .El t Xo .Nm .Cm create .Op Fl ps .Op Fl b Ar blocksize .Oo Fl o Ar property Ns = Ns Ar value Oc Ns ... .Fl V Ar size Ar volume .Xc Creates a volume of the given size. The volume is exported as a block device in

a /dev/zvol/{dsk,rdsk}/path , where .Em path is the name of the volume in the ZFS namespace. The size represents the logical size as exported by the device. By default, a reservation of equal size is created.

p .Ar size is automatically rounded up to the nearest 128 Kbytes to ensure that the volume has an integral number of blocks regardless of .Sy blocksize . l -tag -width "-b" t Fl b Ar blocksize Equivalent to .Fl o Sy volblocksize Ns = Ns Ar blocksize . If this option is specified in conjunction with .Fl o Sy volblocksize , the resulting behavior is undefined. t Fl o Ar property Ns = Ns Ar value Sets the specified property as if the .Nm zfs Cm set Ar property Ns = Ns Ar value command was invoked at the same time the dataset was created. Any editable ZFS property can also be set at creation time. Multiple .Fl o options can be specified. An error results if the same property is specified in multiple .Fl o options. t Fl p Creates all the non-existing parent datasets. Datasets created in this manner are automatically mounted according to the .Sy mountpoint property inherited from their parent. Any property specified on the command line using the .Fl o option is ignored. If the target filesystem already exists, the operation completes successfully. t Fl s Creates a sparse volume with no reservation. See .Sy volsize in the .Sx Native Properties section for more information about sparse volumes. .El t Xo .Nm .Cm destroy .Op Fl Rfnprv .Ar filesystem Ns | Ns Ar volume .Xc Destroys the given dataset. By default, the command unshares any file systems that are currently shared, unmounts any file systems that are currently mounted, and refuses to destroy a dataset that has active dependents

q children or clones . l -tag -width "-R" t Fl R Recursively destroy all dependents, including cloned file systems outside the target hierarchy. t Fl f Force an unmount of any file systems using the .Nm unmount Fl f command. This option has no effect on non-file systems or unmounted file systems. t Fl n Do a dry-run

q Qq No-op deletion. No data will be deleted. This is useful in conjunction with the .Fl v or .Fl p flags to determine what data would be deleted. t Fl p Print machine-parsable verbose information about the deleted data. t Fl r Recursively destroy all children. t Fl v Print verbose information about the deleted data. .El

p Extreme care should be taken when applying either the .Fl r or the .Fl R options, as they can destroy large portions of a pool and cause unexpected behavior for mounted file systems in use. t Xo .Nm .Cm destroy .Op Fl Rdnprv .Ar filesystem Ns | Ns Ar volume Ns @ Ns Ar snap Ns .Oo % Ns Ar snap Ns Oo , Ns Ar snap Ns Oo % Ns Ar snap Oc Oc Oc Ns ... .Xc The given snapshots are destroyed immediately if and only if the .Nm zfs Cm destroy command without the .Fl d option would have destroyed it. Such immediate destruction would occur, for example, if the snapshot had no clones and the user-initiated reference count were zero.

p If a snapshot does not qualify for immediate destruction, it is marked for deferred deletion. In this state, it exists as a usable, visible snapshot until both of the preconditions listed above are met, at which point it is destroyed.

p An inclusive range of snapshots may be specified by separating the first and last snapshots with a percent sign. The first and/or last snapshots may be left blank, in which case the filesystem's oldest or newest snapshot will be implied.

p Multiple snapshots

q or ranges of snapshots of the same filesystem or volume may be specified in a comma-separated list of snapshots. Only the snapshot's short name

o the part after the .Sy @

c should be specified when using a range or comma-separated list to identify multiple snapshots. l -tag -width "-R" t Fl R Recursively destroy all clones of these snapshots, including the clones, snapshots, and children. If this flag is specified, the .Fl d flag will have no effect. t Fl d Defer snapshot deletion. t Fl n Do a dry-run

q Qq No-op deletion. No data will be deleted. This is useful in conjunction with the .Fl p or .Fl v flags to determine what data would be deleted. t Fl p Print machine-parsable verbose information about the deleted data. t Fl r Destroy

q or mark for deferred deletion all snapshots with this name in descendent file systems. t Fl v Print verbose information about the deleted data.

p Extreme care should be taken when applying either the .Fl r or the .Fl R options, as they can destroy large portions of a pool and cause unexpected behavior for mounted file systems in use. .El t Xo .Nm .Cm destroy .Ar filesystem Ns | Ns Ar volume Ns # Ns Ar bookmark .Xc The given bookmark is destroyed. t Xo .Nm .Cm snapshot .Op Fl r .Oo Fl o Ar property Ns = Ns value Oc Ns ... .Ar filesystem Ns @ Ns Ar snapname Ns | Ns Ar volume Ns @ Ns Ar snapname Ns ... .Xc Creates snapshots with the given names. All previous modifications by successful system calls to the file system are part of the snapshots. Snapshots are taken atomically, so that all snapshots correspond to the same moment in time. See the .Sx Snapshots section for details. l -tag -width "-o" t Fl o Ar property Ns = Ns Ar value Sets the specified property; see .Nm zfs Cm create for details. t Fl r Recursively create snapshots of all descendent datasets .El t Xo .Nm .Cm rollback .Op Fl Rfr .Ar snapshot .Xc Roll back the given dataset to a previous snapshot. When a dataset is rolled back, all data that has changed since the snapshot is discarded, and the dataset reverts to the state at the time of the snapshot. By default, the command refuses to roll back to a snapshot other than the most recent one. In order to do so, all intermediate snapshots and bookmarks must be destroyed by specifying the .Fl r option.

p The .Fl rR options do not recursively destroy the child snapshots of a recursive snapshot. Only direct snapshots of the specified filesystem are destroyed by either of these options. To completely roll back a recursive snapshot, you must rollback the individual child snapshots. l -tag -width "-R" t Fl R Destroy any more recent snapshots and bookmarks, as well as any clones of those snapshots. t Fl f Used with the .Fl R option to force an unmount of any clone file systems that are to be destroyed. t Fl r Destroy any snapshots and bookmarks more recent than the one specified. .El t Xo .Nm .Cm clone .Op Fl p .Oo Fl o Ar property Ns = Ns Ar value Oc Ns ... .Ar snapshot Ar filesystem Ns | Ns Ar volume .Xc Creates a clone of the given snapshot. See the .Sx Clones section for details. The target dataset can be located anywhere in the ZFS hierarchy, and is created as the same type as the original. l -tag -width "-o" t Fl o Ar property Ns = Ns Ar value Sets the specified property; see .Nm zfs Cm create for details. t Fl p Creates all the non-existing parent datasets. Datasets created in this manner are automatically mounted according to the .Sy mountpoint property inherited from their parent. If the target filesystem or volume already exists, the operation completes successfully. .El t Xo .Nm .Cm promote .Ar clone-filesystem .Xc Promotes a clone file system to no longer be dependent on its .Qq origin snapshot. This makes it possible to destroy the file system that the clone was created from. The clone parent-child dependency relationship is reversed, so that the origin file system becomes a clone of the specified file system.

p The snapshot that was cloned, and any snapshots previous to this snapshot, are now owned by the promoted clone. The space they use moves from the origin file system to the promoted clone, so enough space must be available to accommodate these snapshots. No new space is consumed by this operation, but the space accounting is adjusted. The promoted clone must not have any conflicting snapshot names of its own. The .Cm rename subcommand can be used to rename any conflicting snapshots. t Xo .Nm .Cm rename .Op Fl f .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot

.Nm .Cm rename .Op Fl fp .Ar filesystem Ns | Ns Ar volume .Ar filesystem Ns | Ns Ar volume .Xc Renames the given dataset. The new target can be located anywhere in the ZFS hierarchy, with the exception of snapshots. Snapshots can only be renamed within the parent file system or volume. When renaming a snapshot, the parent file system of the snapshot does not need to be specified as part of the second argument. Renamed file systems can inherit new mount points, in which case they are unmounted and remounted at the new mount point. l -tag -width "-a" t Fl f Force unmount any filesystems that need to be unmounted in the process. t Fl p Creates all the nonexistent parent datasets. Datasets created in this manner are automatically mounted according to the .Sy mountpoint property inherited from their parent. .El t Xo .Nm .Cm rename .Fl r .Ar snapshot Ar snapshot .Xc Recursively rename the snapshots of all descendent datasets. Snapshots are the only dataset that can be renamed recursively. t Xo .Nm .Cm list .Op Fl r Ns | Ns Fl d Ar depth .Op Fl Hp .Oo Fl o Ar property Ns Oo , Ns Ar property Oc Ns ... Oc .Oo Fl s Ar property Oc Ns ... .Oo Fl S Ar property Oc Ns ... .Oo Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Oc .Oo Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Oc Ns ... .Xc Lists the property information for the given datasets in tabular form. If specified, you can list property information by the absolute pathname or the relative pathname. By default, all file systems and volumes are displayed. Snapshots are displayed if the .Sy listsnaps property is .Sy on

o the default is .Sy off

c . The following fields are displayed, .Sy name Ns , Ns Sy used Ns , Ns Sy available Ns , Ns Sy referenced Ns , Ns .Sy mountpoint . l -tag -width "-H" t Fl H Used for scripting mode. Do not print headers and separate fields by a single tab instead of arbitrary white space. t Fl S Ar property Same as the .Fl s option, but sorts by property in descending order. t Fl d Ar depth Recursively display any children of the dataset, limiting the recursion to t Fl o Ar property A comma-separated list of properties to display. The property must be: l -bullet t One of the properties described in the .Sx Native Properties section t A user property t The value .Sy name to display the dataset name t The value .Sy space to display space usage properties on file systems and volumes. This is a shortcut for specifying .Fl o Sy name Ns , Ns Sy avail Ns , Ns Sy used Ns , Ns Sy usedsnap Ns , Ns .Sy usedds Ns , Ns Sy usedrefreserv Ns , Ns Sy usedchild Fl t .Sy filesystem Ns , Ns Sy volume syntax. .El t Fl p Display numbers in parsable

q exact values. t Fl r Recursively display any children of the dataset on the command line. .Ar depth . A depth of .Sy 1 will display only the dataset and its direct children. t Fl s Ar property A property for sorting the output by column in ascending order based on the value of the property. The property must be one of the properties described in the .Sx Properties section, or the special value .Sy name to sort by the dataset name. Multiple properties can be specified at one time using multiple .Fl s property options. Multiple .Fl s options are evaluated from left to right in decreasing order of importance. The following is a list of sorting criteria: l -bullet t Numeric types sort in numeric order. t String types sort in alphabetical order. t Types inappropriate for a row sort that row to the literal bottom, regardless of the specified ordering. .El

p If no sorting options are specified the existing behavior of .Nm zfs Cm list is preserved. t Fl t Ar type A comma-separated list of types to display, where .Ar type is one of .Sy filesystem , .Sy snapshot , .Sy volume , .Sy bookmark , or .Sy all . For example, specifying .Fl t Sy snapshot displays only snapshots. .El t Xo .Nm .Cm set .Ar property Ns = Ns Ar value Oo Ar property Ns = Ns Ar value Oc Ns ... .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Ns ... .Xc Sets the property or list of properties to the given value(s) for each dataset. Only some properties can be edited. See the .Sx Properties section for more information on what properties can be set and acceptable values. Numeric values can be specified as exact values, or in a human-readable form with a suffix of .Sy B , K , M , G , T , P , E , Z

o for bytes, kilobytes, megabytes, gigabytes, terabytes, petabytes, exabytes, or zettabytes, respectively

c . User properties can be set on snapshots. For more information, see the .Sx User Properties section. t Xo .Nm .Cm get .Op Fl r Ns | Ns Fl d Ar depth .Op Fl Hp .Oo Fl o Ar field Ns Oo , Ns Ar field Oc Ns ... Oc .Oo Fl s Ar source Ns Oo , Ns Ar source Oc Ns ... Oc .Oo Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Oc .Cm all | Ar property Ns Oo , Ns Ar property Oc Ns ... .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Ns ... .Xc Displays properties for the given datasets. If no datasets are specified, then the command displays properties for all datasets on the system. For each property, the following columns are displayed: d -literal name Dataset name property Property name value Property value source Property source. Can either be local, default, temporary, inherited, or none (-). .Ed

p All columns are displayed by default, though this can be controlled by using the .Fl o option. This command takes a comma-separated list of properties as described in the .Sx Native Properties and .Sx User Properties sections.

p The special value .Sy all can be used to display all properties that apply to the given dataset's type

q filesystem, volume, snapshot, or bookmark . l -tag -width "-H" t Fl H Display output in a form more easily parsed by scripts. Any headers are omitted, and fields are explicitly separated by a single tab instead of an arbitrary amount of space. t Fl d Ar depth Recursively display any children of the dataset, limiting the recursion to .Ar depth . A depth of .Sy 1 will display only the dataset and its direct children. t Fl o Ar field A comma-separated list of columns to display. .Sy name Ns , Ns Sy property Ns , Ns Sy value Ns , Ns Sy source is the default value. t Fl p Display numbers in parsable

q exact values. t Fl r Recursively display properties for any children. t Fl s Ar source A comma-separated list of sources to display. Those properties coming from a source other than those in this list are ignored. Each source must be one of the following: .Sy local , .Sy default , .Sy inherited , .Sy temporary , and .Sy none . The default value is all sources. t Fl t Ar type A comma-separated list of types to display, where .Ar type is one of .Sy filesystem , .Sy snapshot , .Sy volume , .Sy bookmark , or .Sy all . .El t Xo .Nm .Cm inherit .Op Fl rS .Ar property Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Ns ... .Xc Clears the specified property, causing it to be inherited from an ancestor, restored to default if no ancestor has the property set, or with the .Fl S option reverted to the received value if one exists. See the .Sx Properties section for a listing of default values, and details on which properties can be inherited. l -tag -width "-r" t Fl r Recursively inherit the given property for all children. t Fl S Revert the property to the received value if one exists; otherwise operate as if the .Fl S option was not specified. .El t Xo .Nm .Cm upgrade .Xc Displays a list of file systems that are not the most recent version. t Xo .Nm .Cm upgrade .Fl v .Xc Displays a list of currently supported file system versions. t Xo .Nm .Cm upgrade .Op Fl r .Op Fl V Ar version .Fl a | Ar filesystem .Xc Upgrades file systems to a new on-disk version. Once this is done, the file systems will no longer be accessible on systems running older versions of the software. .Nm zfs Cm send streams generated from new snapshots of these file systems cannot be accessed on systems running older versions of the software.

p In general, the file system version is independent of the pool version. See .Xr zpool 1M for information on the .Nm zpool Cm upgrade command.

p In some cases, the file system version and the pool version are interrelated and the pool version must be upgraded before the file system version can be upgraded. l -tag -width "-V" t Fl V Ar version Upgrade to the specified .Ar version . If the .Fl V flag is not specified, this command upgrades to the most recent version. This option can only be used to increase the version number, and only up to the most recent version supported by this software. t Fl a Upgrade all file systems on all imported pools. t Ar filesystem Upgrade the specified file system. t Fl r Upgrade the specified file system and all descendent file systems. .El t Xo .Nm .Cm userspace .Op Fl Hinp .Oo Fl o Ar field Ns Oo , Ns Ar field Oc Ns ... Oc .Oo Fl s Ar field Oc Ns ... .Oo Fl S Ar field Oc Ns ... .Oo Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Oc .Ar filesystem Ns | Ns Ar snapshot .Xc Displays space consumed by, and quotas on, each user in the specified filesystem or snapshot. This corresponds to the .Sy userused@ Ns Em user and .Sy userquota@ Ns Em user properties. l -tag -width "-H" t Fl H Do not print headers, use tab-delimited output. t Fl S Ar field Sort by this field in reverse order. See .Fl s . t Fl i Translate SID to POSIX ID. The POSIX ID may be ephemeral if no mapping exists. Normal POSIX interfaces

o for example, .Xr stat 2 , .Nm ls Fl l

c perform this translation, so the .Fl i option allows the output from .Nm zfs Cm userspace to be compared directly with those utilities. However, .Fl i may lead to confusion if some files were created by an SMB user before a SMB-to-POSIX name mapping was established. In such a case, some files will be owned by the SMB entity and some by the POSIX entity. However, the .Fl i option will report that the POSIX entity has the total usage and quota for both. t Fl n Print numeric ID instead of user/group name. t Fl o Ar field Ns Oo , Ns Ar field Oc Ns ... Display only the specified fields from the following set: .Sy type , .Sy name , .Sy used , .Sy quota . The default is to display all fields. t Fl p Use exact

q parsable numeric output. t Fl s Ar field Sort output by this field. The .Fl s and .Fl S flags may be specified multiple times to sort first by one field, then by another. The default is .Fl s Sy type Fl s Sy name . t Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Print only the specified types from the following set: .Sy all , .Sy posixuser , .Sy smbuser , .Sy posixgroup , .Sy smbgroup . The default is .Fl t Sy posixuser Ns , Ns Sy smbuser . The default can be changed to include group types. .El t Xo .Nm .Cm groupspace .Op Fl Hinp .Oo Fl o Ar field Ns Oo , Ns Ar field Oc Ns ... Oc .Oo Fl s Ar field Oc Ns ... .Oo Fl S Ar field Oc Ns ... .Oo Fl t Ar type Ns Oo , Ns Ar type Oc Ns ... Oc .Ar filesystem Ns | Ns Ar snapshot .Xc Displays space consumed by, and quotas on, each group in the specified filesystem or snapshot. This subcommand is identical to .Nm zfs Cm userspace , except that the default types to display are .Fl t Sy posixgroup Ns , Ns Sy smbgroup . t Xo .Nm .Cm mount .Xc Displays all ZFS file systems currently mounted. t Xo .Nm .Cm mount .Op Fl Ov .Op Fl o Ar options .Fl a | Ar filesystem .Xc Mounts ZFS file systems. l -tag -width "-O" t Fl O Perform an overlay mount. See .Xr mount 1M for more information. t Fl a Mount all available ZFS file systems. Invoked automatically as part of the boot process. t Ar filesystem Mount the specified filesystem. t Fl o Ar options An optional, comma-separated list of mount options to use temporarily for the duration of the mount. See the .Sx Temporary Mount Point Properties section for details. t Fl v Report mount progress. .El t Xo .Nm .Cm unmount .Op Fl f .Fl a | Ar filesystem Ns | Ns Ar mountpoint .Xc Unmounts currently mounted ZFS file systems. l -tag -width "-a" t Fl a Unmount all available ZFS file systems. Invoked automatically as part of the shutdown process. t Ar filesystem Ns | Ns Ar mountpoint Unmount the specified filesystem. The command can also be given a path to a ZFS file system mount point on the system. t Fl f Forcefully unmount the file system, even if it is currently in use. .El t Xo .Nm .Cm share .Fl a | Ar filesystem .Xc Shares available ZFS file systems. l -tag -width "-a" t Fl a Share all available ZFS file systems. Invoked automatically as part of the boot process. t Ar filesystem Share the specified filesystem according to the .Sy sharenfs and .Sy sharesmb properties. File systems are shared when the .Sy sharenfs or .Sy sharesmb property is set. .El t Xo .Nm .Cm unshare .Fl a | Ar filesystem Ns | Ns Ar mountpoint .Xc Unshares currently shared ZFS file systems. l -tag -width "-a" t Fl a Unshare all available ZFS file systems. Invoked automatically as part of the shutdown process. t Ar filesystem Ns | Ns Ar mountpoint Unshare the specified filesystem. The command can also be given a path to a ZFS file system shared on the system. .El t Xo .Nm .Cm bookmark .Ar snapshot bookmark .Xc Creates a bookmark of the given snapshot. Bookmarks mark the point in time when the snapshot was created, and can be used as the incremental source for a .Nm zfs Cm send command.

p This feature must be enabled to be used. See .Xr zpool-features 5 for details on ZFS feature flags and the .Sy bookmarks feature. t Xo .Nm .Cm send .Op Fl DLPRenpv .Op Oo Fl I Ns | Ns Fl i Oc Ar snapshot .Ar snapshot .Xc Creates a stream representation of the second .Ar snapshot , which is written to standard output. The output can be redirected to a file or to a different system

o for example, using .Xr ssh 1

c . By default, a full stream is generated. l -tag -width "-D" t Fl D Generate a deduplicated stream. Blocks which would have been sent multiple times in the send stream will only be sent once. The receiving system must also support this feature to recieve a deduplicated stream. This flag can be used regardless of the dataset's .Sy dedup property, but performance will be much better if the filesystem uses a dedup-capable checksum

o for example, .Sy sha256

c . t Fl I Ar snapshot Generate a stream package that sends all intermediary snapshots from the first snapshot to the second snapshot. For example, .Fl I Em @a Em fs@d is similar to .Fl i Em @a Em fs@b Ns ; Fl i Em @b Em fs@c Ns ; Fl i Em @c Em fs@d . The incremental source may be specified as with the .Fl i option. t Fl L Generate a stream which may contain blocks larger than 128KB. This flag has no effect if the .Sy large_blocks pool feature is disabled, or if the .Sy recordsize property of this filesystem has never been set above 128KB. The receiving system must have the .Sy large_blocks pool feature enabled as well. See .Xr zpool-features 5 for details on ZFS feature flags and the .Sy large_blocks feature. t Fl P Print machine-parsable verbose information about the stream package generated. t Fl R Generate a replication stream package, which will replicate the specified file system, and all descendent file systems, up to the named snapshot. When received, all properties, snapshots, descendent file systems, and clones are preserved.

p If the .Fl i or .Fl I flags are used in conjunction with the .Fl R flag, an incremental replication stream is generated. The current values of properties, and current snapshot and file system names are set when the stream is received. If the .Fl F flag is specified when this stream is received, snapshots and file systems that do not exist on the sending side are destroyed. t Fl e Generate a more compact stream by using .Sy WRITE_EMBEDDED records for blocks which are stored more compactly on disk by the .Sy embedded_data pool feature. This flag has no effect if the .Sy embedded_data feature is disabled. The receiving system must have the .Sy embedded_data feature enabled. If the .Sy lz4_compress feature is active on the sending system, then the receiving system must have that feature enabled as well. See .Xr zpool-features 5 for details on ZFS feature flags and the .Sy embedded_data feature. t Fl i Ar snapshot Generate an incremental stream from the first .Ar snapshot

q the incremental source to the second .Ar snapshot

q the incremental target . The incremental source can be specified as the last component of the snapshot name

o the .Sy @ character and following

c and it is assumed to be from the same file system as the incremental target.

p If the destination is a clone, the source may be the origin snapshot, which must be fully specified

o for example, .Em pool/fs@origin , not just .Em @origin

c . t Fl n Do a dry-run

q Qq No-op send. Do not generate any actual send data. This is useful in conjunction with the .Fl v or .Fl P flags to determine what data will be sent. In this case, the verbose output will be written to standard output

o contrast with a non-dry-run, where the stream is written to standard output and the verbose output goes to standard error

c . t Fl p Include the dataset's properties in the stream. This flag is implicit when .Fl R is specified. The receiving system must also support this feature. t Fl v Print verbose information about the stream package generated. This information includes a per-second report of how much data has been sent.

p The format of the stream is committed. You will be able to receive your streams on future versions of ZFS . .El t Xo .Nm .Cm send .Op Fl Le .Op Fl i Ar snapshot Ns | Ns Ar bookmark .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot .Xc Generate a send stream, which may be of a filesystem, and may be incremental from a bookmark. If the destination is a filesystem or volume, the pool must be read-only, or the filesystem must not be mounted. When the stream generated from a filesystem or volume is received, the default snapshot name will be .Qq --head-- . l -tag -width "-L" t Fl L Generate a stream which may contain blocks larger than 128KB. This flag has no effect if the .Sy large_blocks pool feature is disabled, or if the .Sy recordsize property of this filesystem has never been set above 128KB. The receiving system must have the .Sy large_blocks pool feature enabled as well. See .Xr zpool-features 5 for details on ZFS feature flags and the .Sy large_blocks feature. t Fl e Generate a more compact stream by using .Sy WRITE_EMBEDDED records for blocks which are stored more compactly on disk by the .Sy embedded_data pool feature. This flag has no effect if the .Sy embedded_data feature is disabled. The receiving system must have the .Sy embedded_data feature enabled. If the .Sy lz4_compress feature is active on the sending system, then the receiving system must have that feature enabled as well. See .Xr zpool-features 5 for details on ZFS feature flags and the .Sy embedded_data feature. t Fl i Ar snapshot Ns | Ns Ar bookmark Generate an incremental send stream. The incremental source must be an earlier snapshot in the destination's history. It will commonly be an earlier snapshot in the destination's file system, in which case it can be specified as the last component of the name

o the .Sy # or .Sy @ character and following

c .

p If the incremental target is a clone, the incremental source can be the origin snapshot, or an earlier snapshot in the origin's filesystem, or the origin's origin, etc. .El t Xo .Nm .Cm send .Op Fl Penv .Fl t .Ar receive_resume_token .Xc Creates a send stream which resumes an interrupted receive. The .Ar receive_resume_token is the value of this property on the filesystem or volume that was being received into. See the documentation for .Sy zfs receive -s for more details. t Xo .Nm .Cm receive .Op Fl Fnsuv .Op Fl o Sy origin Ns = Ns Ar snapshot .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot

.Nm .Cm receive .Op Fl Fnsuv .Op Fl d Ns | Ns Fl e .Op Fl o Sy origin Ns = Ns Ar snapshot .Ar filesystem .Xc Creates a snapshot whose contents are as specified in the stream provided on standard input. If a full stream is received, then a new file system is created as well. Streams are created using the .Nm zfs Cm send subcommand, which by default creates a full stream. .Nm zfs Cm recv can be used as an alias for .Nm zfs Cm receive.

p If an incremental stream is received, then the destination file system must already exist, and its most recent snapshot must match the incremental stream's source. For .Sy zvols , the destination device link is destroyed and recreated, which means the .Sy zvol cannot be accessed during the .Cm receive operation.

p When a snapshot replication package stream that is generated by using the .Nm zfs Cm send Fl R command is received, any snapshots that do not exist on the sending location are destroyed by using the .Nm zfs Cm destroy Fl d command.

p The name of the snapshot

q and file system, if a full stream is received that this subcommand creates depends on the argument type and the use of the .Fl d or .Fl e options.

p If the argument is a snapshot name, the specified .Ar snapshot is created. If the argument is a file system or volume name, a snapshot with the same name as the sent snapshot is created within the specified .Ar filesystem or .Ar volume . If neither of the .Fl d or .Fl e options are specified, the provided target snapshot name is used exactly as provided.

p The .Fl d and .Fl e options cause the file system name of the target snapshot to be determined by appending a portion of the sent snapshot's name to the specified target .Ar filesystem . If the .Fl d option is specified, all but the first element of the sent snapshot's file system path

q usually the pool name is used and any required intermediate file systems within the specified one are created. If the .Fl e option is specified, then only the last element of the sent snapshot's file system name

q i.e. the name of the source file system itself is used as the target file system name. l -tag -width "-F" t Fl F Force a rollback of the file system to the most recent snapshot before performing the receive operation. If receiving an incremental replication stream

o for example, one generated by .Nm zfs Cm send Fl R Op Fl i Ns | Ns Fl I

c , destroy snapshots and file systems that do not exist on the sending side. t Fl d Discard the first element of the sent snapshot's file system name, using the remaining elements to determine the name of the target file system for the new snapshot as described in the paragraph above. t Fl e Discard all but the last element of the sent snapshot's file system name, using that element to determine the name of the target file system for the new snapshot as described in the paragraph above. t Fl n Do not actually receive the stream. This can be useful in conjunction with the .Fl v option to verify the name the receive operation would use. t Fl o Sy origin Ns = Ns Ar snapshot Forces the stream to be received as a clone of the given snapshot. If the stream is a full send stream, this will create the filesystem described by the stream as a clone of the specified snapshot. Which snapshot was specified will not affect the success or failure of the receive, as long as the snapshot does exist. If the stream is an incremental send stream, all the normal verification will be performed. t Fl u File system that is associated with the received stream is not mounted. t Fl v Print verbose information about the stream and the time required to perform the receive operation. t Fl s If the receive is interrupted, save the partially received state, rather than deleting it. Interruption may be due to premature termination of the stream

o e.g. due to network failure or failure of the remote system if the stream is being read over a network connection

c , a checksum error in the stream, termination of the .Nm zfs Cm receive process, or unclean shutdown of the system.

p The receive can be resumed with a stream generated by .Nm zfs Cm send Fl t Ar token , where the .Ar token is the value of the .Sy receive_resume_token property of the filesystem or volume which is received into.

p To use this flag, the storage pool must have the .Sy extensible_dataset feature enabled. See .Xr zpool-features 5 for details on ZFS feature flags. .El t Xo .Nm .Cm receive .Fl A .Ar filesystem Ns | Ns Ar volume .Xc Abort an interrupted .Nm zfs Cm receive Fl s , deleting its saved partially received state. t Xo .Nm .Cm allow .Ar filesystem Ns | Ns Ar volume .Xc Displays permissions that have been delegated on the specified filesystem or volume. See the other forms of .Nm zfs Cm allow for more information. t Xo .Nm .Cm allow .Op Fl dglu .Ar user Ns | Ns Ar group Ns Oo , Ns Ar user Ns | Ns Ar group Oc Ns ... .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Ar filesystem Ns | Ns Ar volume

.Nm .Cm allow .Op Fl dl .Fl e Ns | Ns Sy everyone .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Ar filesystem Ns | Ns Ar volume .Xc Delegates ZFS administration permission for the file systems to non-privileged users. l -tag -width "-d" t Fl d Allow only for the descendent file systems. t Fl e Ns | Ns Sy everyone Specifies that the permissions be delegated to everyone. t Fl g Ar group Ns Oo , Ns Ar group Oc Ns ... Explicitly specify that permissions are delegated to the group. t Fl l Allow .Qq locally only for the specified file system. t Fl u Ar user Ns Oo , Ns Ar user Oc Ns ... Explicitly specify that permissions are delegated to the user. t Ar user Ns | Ns Ar group Ns Oo , Ns Ar user Ns | Ns Ar group Oc Ns ... Specifies to whom the permissions are delegated. Multiple entities can be specified as a comma-separated list. If neither of the .Fl gu options are specified, then the argument is interpreted preferentially as the keyword .Sy everyone , then as a user name, and lastly as a group name. To specify a user or group named .Qq everyone , use the .Fl g or .Fl u options. To specify a group with the same name as a user, use the .Fl g options. t Xo .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Xc The permissions to delegate. Multiple permissions may be specified as a comma-separated list. Permission names are the same as ZFS subcommand and property names. See the property list below. Property set names, which begin with .Sy @ , may be specified. See the .Fl s form below for details. .El

p If neither of the .Fl dl options are specified, or both are, then the permissions are allowed for the file system or volume, and all of its descendents.

p Permissions are generally the ability to use a ZFS subcommand or change a ZFS property. The following permissions are available: d -literal NAME TYPE NOTES allow subcommand Must also have the permission that is being allowed clone subcommand Must also have the 'create' ability and 'mount' ability in the origin file system create subcommand Must also have the 'mount' ability destroy subcommand Must also have the 'mount' ability diff subcommand Allows lookup of paths within a dataset given an object number, and the ability to create snapshots necessary to 'zfs diff'. mount subcommand Allows mount/umount of ZFS datasets promote subcommand Must also have the 'mount' and 'promote' ability in the origin file system receive subcommand Must also have the 'mount' and 'create' ability rename subcommand Must also have the 'mount' and 'create' ability in the new parent rollback subcommand Must also have the 'mount' ability send subcommand share subcommand Allows sharing file systems over NFS or SMB protocols snapshot subcommand Must also have the 'mount' ability groupquota other Allows accessing any groupquota@... property groupused other Allows reading any groupused@... property userprop other Allows changing any user property userquota other Allows accessing any userquota@... property userused other Allows reading any userused@... property aclinherit property aclmode property atime property canmount property casesensitivity property checksum property compression property copies property devices property exec property filesystem_limit property mountpoint property nbmand property normalization property primarycache property quota property readonly property recordsize property refquota property refreservation property reservation property secondarycache property setuid property sharenfs property sharesmb property snapdir property snapshot_limit property utf8only property version property volblocksize property volsize property vscan property xattr property zoned property .Ed t Xo .Nm .Cm allow .Fl c .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Ar filesystem Ns | Ns Ar volume .Xc Sets .Qq create time permissions. These permissions are granted

q locally to the creator of any newly-created descendent file system. t Xo .Nm .Cm allow .Fl s No @ Ns Ar setname .Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... .Ar filesystem Ns | Ns Ar volume .Xc Defines or adds permissions to a permission set. The set can be used by other .Nm zfs Cm allow commands for the specified file system and its descendents. Sets are evaluated dynamically, so changes to a set are immediately reflected. Permission sets follow the same naming restrictions as ZFS file systems, but the name must begin with .Sy @ , and can be no more than 64 characters long. t Xo .Nm .Cm unallow .Op Fl dglru .Ar user Ns | Ns Ar group Ns Oo , Ns Ar user Ns | Ns Ar group Oc Ns ... .Oo Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... Oc .Ar filesystem Ns | Ns Ar volume

.Nm .Cm unallow .Op Fl dlr .Fl e Ns | Ns Sy everyone .Oo Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... Oc .Ar filesystem Ns | Ns Ar volume

.Nm .Cm unallow .Op Fl r .Fl c .Oo Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... Oc .Ar filesystem Ns | Ns Ar volume .Xc Removes permissions that were granted with the .Nm zfs Cm allow command. No permissions are explicitly denied, so other permissions granted are still in effect. For example, if the permission is granted by an ancestor. If no permissions are specified, then all permissions for the specified .Ar user , .Ar group , or .Sy everyone are removed. Specifying .Sy everyone

o or using the .Fl e option

c only removes the permissions that were granted to everyone, not all permissions for every user and group. See the .Nm zfs Cm allow command for a description of the .Fl ldugec options. l -tag -width "-r" t Fl r Recursively remove the permissions from this file system and all descendents. .El t Xo .Nm .Cm unallow .Op Fl r .Fl s @ Ns Ar setname .Oo Ar perm Ns | Ns @ Ns Ar setname Ns Oo , Ns Ar perm Ns | Ns @ Ns .Ar setname Oc Ns ... Oc .Ar filesystem Ns | Ns Ar volume .Xc Removes permissions from a permission set. If no permissions are specified, then all permissions are removed, thus removing the set entirely. t Xo .Nm .Cm hold .Op Fl r .Ar tag Ar snapshot Ns ... .Xc Adds a single reference, named with the .Ar tag argument, to the specified snapshot or snapshots. Each snapshot has its own tag namespace, and tags must be unique within that space.

p If a hold exists on a snapshot, attempts to destroy that snapshot by using the .Nm zfs Cm destroy command return .Er EBUSY . l -tag -width "-r" t Fl r Specifies that a hold with the given tag is applied recursively to the snapshots of all descendent file systems. .El t Xo .Nm .Cm holds .Op Fl r .Ar snapshot Ns ... .Xc Lists all existing user references for the given snapshot or snapshots. l -tag -width "-r" t Fl r Lists the holds that are set on the named descendent snapshots, in addition to listing the holds on the named snapshot. .El t Xo .Nm .Cm release .Op Fl r .Ar tag Ar snapshot Ns ... .Xc Removes a single reference, named with the .Ar tag argument, from the specified snapshot or snapshots. The tag must already exist for each snapshot. If a hold exists on a snapshot, attempts to destroy that snapshot by using the .Nm zfs Cm destroy command return .Er EBUSY . l -tag -width "-r" t Fl r Recursively releases a hold with the given tag on the snapshots of all descendent file systems. .El t Xo .Nm .Cm diff .Op Fl FHt .Ar snapshot Ar snapshot Ns | Ns Ar filesystem .Xc Display the difference between a snapshot of a given filesystem and another snapshot of that filesystem from a later time or the current contents of the filesystem. The first column is a character indicating the type of change, the other columns indicate pathname, new pathname

q in case of rename , change in link count, and optionally file type and/or change time. The types of change are: d -literal - The path has been removed + The path has been created M The path has been modified R The path has been renamed .Ed l -tag -width "-F" t Fl F Display an indication of the type of file, in a manner similar to the .Fl option of .Xr ls 1 . d -literal B Block device C Character device / Directory > Door | Named pipe @ Symbolic link P Event port = Socket F Regular file .Ed t Fl H Give more parsable tab-separated output, without header lines and without arrows. t Fl t Display the path's inode change time as the first column of output. .El .El .Sh EXIT STATUS The .Nm utility exits 0 on success, 1 if an error occurs, and 2 if invalid command line options were specified. .Sh EXAMPLES l -tag -width "" t Sy Example 1 No Creating a ZFS File System Hierarchy The following commands create a file system named .Em pool/home and a file system named .Em pool/home/bob . The mount point

a /export/home is set for the parent file system, and is automatically inherited by the child file system. d -literal # zfs create pool/home # zfs set mountpoint=/export/home pool/home # zfs create pool/home/bob .Ed t Sy Example 2 No Creating a ZFS Snapshot The following command creates a snapshot named .Sy yesterday . This snapshot is mounted on demand in the

a .zfs/snapshot directory at the root of the .Em pool/home/bob file system. d -literal # zfs snapshot pool/home/bob@yesterday .Ed t Sy Example 3 No Creating and Destroying Multiple Snapshots The following command creates snapshots named .Sy yesterday of .Em pool/home and all of its descendent file systems. Each snapshot is mounted on demand in the

a .zfs/snapshot directory at the root of its file system. The second command destroys the newly created snapshots. d -literal # zfs snapshot -r pool/home@yesterday # zfs destroy -r pool/home@yesterday .Ed t Sy Example 4 No Disabling and Enabling File System Compression The following command disables the .Sy compression property for all file systems under .Em pool/home . The next command explicitly enables .Sy compression for .Em pool/home/anne . d -literal # zfs set compression=off pool/home # zfs set compression=on pool/home/anne .Ed t Sy Example 5 No Listing ZFS Datasets The following command lists all active file systems and volumes in the system. Snapshots are displayed if the .Sy listsnaps property is .Sy on . The default is .Sy off . See .Xr zpool 1M for more information on pool properties. d -literal # zfs list NAME USED AVAIL REFER MOUNTPOINT pool 450K 457G 18K /pool pool/home 315K 457G 21K /export/home pool/home/anne 18K 457G 18K /export/home/anne pool/home/bob 276K 457G 276K /export/home/bob .Ed t Sy Example 6 No Setting a Quota on a ZFS File System The following command sets a quota of 50 Gbytes for .Em pool/home/bob . d -literal # zfs set quota=50G pool/home/bob .Ed t Sy Example 7 No Listing ZFS Properties The following command lists all properties for .Em pool/home/bob . d -literal # zfs get all pool/home/bob NAME PROPERTY VALUE SOURCE pool/home/bob type filesystem - pool/home/bob creation Tue Jul 21 15:53 2009 - pool/home/bob used 21K - pool/home/bob available 20.0G - pool/home/bob referenced 21K - pool/home/bob compressratio 1.00x - pool/home/bob mounted yes - pool/home/bob quota 20G local pool/home/bob reservation none default pool/home/bob recordsize 128K default pool/home/bob mountpoint /pool/home/bob default pool/home/bob sharenfs off default pool/home/bob checksum on default pool/home/bob compression on local pool/home/bob atime on default pool/home/bob devices on default pool/home/bob exec on default pool/home/bob setuid on default pool/home/bob readonly off default pool/home/bob zoned off default pool/home/bob snapdir hidden default pool/home/bob aclmode discard default pool/home/bob aclinherit restricted default pool/home/bob canmount on default pool/home/bob xattr on default pool/home/bob copies 1 default pool/home/bob version 4 - pool/home/bob utf8only off - pool/home/bob normalization none - pool/home/bob casesensitivity sensitive - pool/home/bob vscan off default pool/home/bob nbmand off default pool/home/bob sharesmb off default pool/home/bob refquota none default pool/home/bob refreservation none default pool/home/bob primarycache all default pool/home/bob secondarycache all default pool/home/bob usedbysnapshots 0 - pool/home/bob usedbydataset 21K - pool/home/bob usedbychildren 0 - pool/home/bob usedbyrefreservation 0 - .Ed

p The following command gets a single property value. d -literal # zfs get -H -o value compression pool/home/bob on .Ed The following command lists all properties with local settings for .Em pool/home/bob . d -literal # zfs get -r -s local -o name,property,value all pool/home/bob NAME PROPERTY VALUE pool/home/bob quota 20G pool/home/bob compression on .Ed t Sy Example 8 No Rolling Back a ZFS File System The following command reverts the contents of .Em pool/home/anne to the snapshot named .Sy yesterday , deleting all intermediate snapshots. d -literal # zfs rollback -r pool/home/anne@yesterday .Ed t Sy Example 9 No Creating a ZFS Clone The following command creates a writable file system whose initial contents are the same as .Em pool/home/bob@yesterday . d -literal # zfs clone pool/home/bob@yesterday pool/clone .Ed t Sy Example 10 No Promoting a ZFS Clone The following commands illustrate how to test out changes to a file system, and then replace the original file system with the changed one, using clones, clone promotion, and renaming: d -literal # zfs create pool/project/production populate /pool/project/production with data # zfs snapshot pool/project/production@today # zfs clone pool/project/production@today pool/project/beta make changes to /pool/project/beta and test them # zfs promote pool/project/beta # zfs rename pool/project/production pool/project/legacy # zfs rename pool/project/beta pool/project/production once the legacy version is no longer needed, it can be destroyed # zfs destroy pool/project/legacy .Ed t Sy Example 11 No Inheriting ZFS Properties The following command causes .Em pool/home/bob and .Em pool/home/anne to inherit the .Sy checksum property from their parent. d -literal # zfs inherit checksum pool/home/bob pool/home/anne .Ed t Sy Example 12 No Remotely Replicating ZFS Data The following commands send a full stream and then an incremental stream to a remote machine, restoring them into .Em poolB/received/fs@a and .Em poolB/received/fs@b , respectively. .Em poolB must contain the file system .Em poolB/received , and must not initially contain .Em poolB/received/fs . d -literal # zfs send pool/fs@a | \e ssh host zfs receive poolB/received/fs@a # zfs send -i a pool/fs@b | \e ssh host zfs receive poolB/received/fs .Ed t Sy Example 13 No Using the zfs receive -d Option The following command sends a full stream of .Em poolA/fsA/fsB@snap to a remote machine, receiving it into .Em poolB/received/fsA/fsB@snap . The .Em fsA/fsB@snap portion of the received snapshot's name is determined from the name of the sent snapshot. .Em poolB must contain the file system .Em poolB/received . If .Em poolB/received/fsA does not exist, it is created as an empty file system. d -literal # zfs send poolA/fsA/fsB@snap | \e ssh host zfs receive -d poolB/received .Ed t Sy Example 14 No Setting User Properties The following example sets the user-defined .Sy com.example:department property for a dataset. d -literal # zfs set com.example:department=12345 tank/accounting .Ed t Sy Example 15 No Performing a Rolling Snapshot The following example shows how to maintain a history of snapshots with a consistent naming scheme. To keep a week's worth of snapshots, the user destroys the oldest snapshot, renames the remaining snapshots, and then creates a new snapshot, as follows: d -literal # zfs destroy -r pool/users@7daysago # zfs rename -r pool/users@6daysago @7daysago # zfs rename -r pool/users@5daysago @6daysago # zfs rename -r pool/users@yesterday @5daysago # zfs rename -r pool/users@yesterday @4daysago # zfs rename -r pool/users@yesterday @3daysago # zfs rename -r pool/users@yesterday @2daysago # zfs rename -r pool/users@today @yesterday # zfs snapshot -r pool/users@today .Ed t Sy Example 16 No Setting sharenfs Property Options on a ZFS File System The following commands show how to set .Sy sharenfs property options to enable .Sy rw access for a set of .Sy IP addresses and to enable root access for system .Sy neo on the .Em tank/home file system. d -literal # zfs set sharenfs='rw=@123.123.0.0/16,root=neo' tank/home .Ed

p If you are using .Sy DNS for host name resolution, specify the fully qualified hostname. t Sy Example 17 No Delegating ZFS Administration Permissions on a ZFS Dataset The following example shows how to set permissions so that user .Sy cindys can create, destroy, mount, and take snapshots on .Em tank/cindys . The permissions on .Em tank/cindys are also displayed. d -literal # zfs allow cindys create,destroy,mount,snapshot tank/cindys # zfs allow tank/cindys ---- Permissions on tank/cindys -------------------------------------- Local+Descendent permissions: user cindys create,destroy,mount,snapshot .Ed

p Because the .Em tank/cindys mount point permission is set to 755 by default, user .Sy cindys will be unable to mount file systems under .Em tank/cindys . Add an ACE similar to the following syntax to provide mount point access: d -literal # chmod A+user:cindys:add_subdirectory:allow /tank/cindys .Ed t Sy Example 18 No Delegating Create Time Permissions on a ZFS Dataset The following example shows how to grant anyone in the group .Sy staff to create file systems in .Em tank/users . This syntax also allows staff members to destroy their own file systems, but not destroy anyone else's file system. The permissions on .Em tank/users are also displayed. d -literal # zfs allow staff create,mount tank/users # zfs allow -c destroy tank/users # zfs allow tank/users ---- Permissions on tank/users --------------------------------------- Permission sets: destroy Local+Descendent permissions: group staff create,mount .Ed t Sy Example 19 No Defining and Granting a Permission Set on a ZFS Dataset The following example shows how to define and grant a permission set on the .Em tank/users file system. The permissions on .Em tank/users are also displayed. d -literal # zfs allow -s @pset create,destroy,snapshot,mount tank/users # zfs allow staff @pset tank/users # zfs allow tank/users ---- Permissions on tank/users --------------------------------------- Permission sets: @pset create,destroy,mount,snapshot Local+Descendent permissions: group staff @pset .Ed t Sy Example 20 No Delegating Property Permissions on a ZFS Dataset The following example shows to grant the ability to set quotas and reservations on the .Em users/home file system. The permissions on .Em users/home are also displayed. d -literal # zfs allow cindys quota,reservation users/home # zfs allow users/home ---- Permissions on users/home --------------------------------------- Local+Descendent permissions: user cindys quota,reservation cindys% zfs set quota=10G users/home/marks cindys% zfs get quota users/home/marks NAME PROPERTY VALUE SOURCE users/home/marks quota 10G local .Ed t Sy Example 21 No Removing ZFS Delegated Permissions on a ZFS Dataset The following example shows how to remove the snapshot permission from the .Sy staff group on the .Em tank/users file system. The permissions on .Em tank/users are also displayed. d -literal # zfs unallow staff snapshot tank/users # zfs allow tank/users ---- Permissions on tank/users --------------------------------------- Permission sets: @pset create,destroy,mount,snapshot Local+Descendent permissions: group staff @pset .Ed t Sy Example 22 No Showing the differences between a snapshot and a ZFS Dataset The following example shows how to see what has changed between a prior snapshot of a ZFS dataset and its current state. The .Fl F option is used to indicate type information for the files affected. d -literal # zfs diff -F tank/test@before tank/test M / /tank/test/ M F /tank/test/linked (+1) R F /tank/test/oldname -> /tank/test/newname - F /tank/test/deleted + F /tank/test/created M F /tank/test/modified .Ed .El .Sh INTERFACE STABILITY .Sy Commited . .Sh SEE ALSO .Xr gzip 1 , .Xr ssh 1 , .Xr mount 1M , .Xr share 1M , .Xr sharemgr 1M , .Xr unshare 1M , .Xr zonecfg 1M , .Xr zpool 1M , .Xr chmod 2 , .Xr stat 2 , .Xr write 2 , .Xr fsync 3C , .Xr dfstab 4 , .Xr acl 5 , .Xr attributes 5