ZFS(8) System Manager's Manual ZFS(8)

zfsconfigure ZFS datasets

zfs -?V

zfs version

zfs subcommand [arguments]

The zfs command configures ZFS datasets within a ZFS storage pool, as described in zpool(8). A dataset is identified by a unique path within the ZFS namespace:


for example:


The maximum length of a dataset name is - 1 ASCII characters (currently 255) satisfying . Additionally snapshots are allowed to contain a single character, while bookmarks are allowed to contain a single character. / is used as separator between components. The maximum amount of nesting allowed in a path is levels deep. ZFS tunables () are explained in zfs(4).

A dataset can be one of the following:

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.
A logical volume exported as a raw or block device. This type of dataset should only be used when a block device is required. File systems are typically used in most environments.
A read-only version of a file system or volume at a given point in time. It is specified as filesystem@name or volume@name.
Much like a snapshot, but without the hold on on-disk data. It can be used as the source of a send (but not for a receive). It is specified as filesystem#name or volume#name.

See zfsconcepts(7) for details.

Properties are divided into two types: native properties and user-defined (or "user") 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 properties, see zfsprops(7).

Enabling the feature allows for the creation of encrypted filesystems and volumes. ZFS will encrypt file and zvol data, file attributes, ACLs, permission bits, directory listings, FUID mappings, and // data. For an overview of encryption, see zfs-load-key(8).

All subcommands that modify state are logged persistently to the pool in their original form.

zfs -?
Displays a help message.
zfs -V, --version
zfs version
Displays the software version of the zfs userland utility and the zfs kernel module.

Lists the property information for the given datasets in tabular form.
Creates a new ZFS file system or volume.
Destroys the given dataset(s), snapshot(s), or bookmark.
Renames the given dataset (filesystem or snapshot).
Manage upgrading the on-disk version of filesystems.

Creates snapshots with the given names.
Roll back the given dataset to a previous snapshot.
Add or remove a hold reference to the specified snapshot or snapshots. If a hold exists on a snapshot, attempts to destroy that snapshot by using the zfs destroy command return .
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.

Creates a clone of the given snapshot.
Promotes a clone file system to no longer be dependent on its "origin" snapshot.

Generate a send stream, which may be of a filesystem, and may be incremental from a bookmark.
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 zfs-send(8) subcommand, which by default creates a full stream.
Creates a new bookmark of the given snapshot or bookmark. Bookmarks mark the point in time when the snapshot was created, and can be used as the incremental source for a zfs send command.
Generate a new redaction bookmark. This feature can be used to allow clones of a filesystem to be made available on a remote system, in the case where their parent need not (or needs to not) be usable.

Displays properties for the given datasets.
Sets the property or list of properties to the given value(s) for each dataset.
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 -S option reverted to the received value if one exists.

Displays space consumed by, and quotas on, each user, group, or project in the specified filesystem or snapshot.
List, set, or clear project ID and/or inherit flag on the files or directories.

Displays all ZFS file systems currently mounted, or mount ZFS filesystem on a path described by its mountpoint property.
Unmounts currently mounted ZFS file systems.

Shares available ZFS file systems.
Unshares currently shared ZFS file systems.

Delegate permissions on the specified filesystem or volume.
Remove delegated permissions on the specified filesystem or volume.

Add or change an encryption key on the specified dataset.
Load the key for the specified encrypted dataset, enabling access.
Unload a key for the specified dataset, removing the ability to access the dataset.

Execute ZFS administrative operations programmatically via a Lua script-language channel program.

Attaches a filesystem to a jail.
Detaches a filesystem from a jail.

Wait for background activity in a filesystem to complete.

The zfs utility exits 0 on success, if an error occurs, and if invalid command line options were specified.

The following commands create a file system named pool/home and a file system named pool/home/bob. The mount point /export/home is set for the parent file system, and is automatically inherited by the child file system.

# zfs create pool/home
# zfs set mountpoint=/export/home pool/home
# zfs create pool/home/bob

The following command creates a snapshot named yesterday. This snapshot is mounted on demand in the .zfs/snapshot directory at the root of the pool/home/bob file system.

# zfs snapshot pool/home/bob@yesterday

The following command creates snapshots named yesterday of pool/home and all of its descendent file systems. Each snapshot is mounted on demand in the .zfs/snapshot directory at the root of its file system. The second command destroys the newly created snapshots.

# zfs snapshot -r pool/home@yesterday
# zfs destroy -r pool/home@yesterday

The following command disables the compression property for all file systems under pool/home. The next command explicitly enables compression for pool/home/anne.

# zfs set compression=off pool/home
# zfs set compression=on pool/home/anne

The following command lists all active file systems and volumes in the system. Snapshots are displayed if =on. The default is off. See zpoolprops(7) for more information on pool properties.

# 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

The following command sets a quota of 50 Gbytes for pool/home/bob:

# zfs set quota=50G pool/home/bob

The following command lists all properties for pool/home/bob:

# zfs get  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  acltype               off                    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                      -

The following command gets a single property value:

# zfs get -H -o value compression pool/home/bob

The following command lists all properties with local settings for pool/home/bob:

# zfs get -r -s  -o ,,value all pool/home/bob
NAME           PROPERTY              VALUE
pool/home/bob  quota                 20G
pool/home/bob  compression           on

The following command reverts the contents of pool/home/anne to the snapshot named yesterday, deleting all intermediate snapshots:

# zfs rollback -r pool/home/anne@yesterday

The following command creates a writable file system whose initial contents are the same as pool/home/bob@yesterday.

# zfs clone pool/home/bob@yesterday pool/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:

# 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

The following command causes pool/home/bob and pool/home/anne to inherit the checksum property from their parent.

# zfs inherit checksum pool/home/bob pool/home/anne

The following commands send a full stream and then an incremental stream to a remote machine, restoring them into and , respectively. must contain the file system , and must not initially contain .

# zfs send pool/fs@a |
    ssh host zfs receive poolB/received/fs@a
# zfs send -i a pool/fs@b |
    ssh host zfs receive poolB/received/fs

The following command sends a full stream of poolA/fsA/fsB@snap to a remote machine, receiving it into poolB/received/fsA/fsB@snap. The fsA/fsB@snap portion of the received snapshot's name is determined from the name of the sent snapshot. poolB must contain the file system poolB/received. If poolB/received/fsA does not exist, it is created as an empty file system.

# zfs send poolA/fsA/fsB@snap |
    ssh host zfs receive -d poolB/received

The following example sets the user-defined com.example:department property for a dataset:

# zfs set com.example:department=12345 tank/accounting

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:

# 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@4daysago @5daysago
# zfs rename -r pool/users@3daysago @4daysago
# zfs rename -r pool/users@2daysago @3daysago
# zfs rename -r pool/users@yesterday @2daysago
# zfs rename -r pool/users@today @yesterday
# zfs snapshot -r pool/users@today

The following commands show how to set sharenfs property options to enable read-write access for a set of IP addresses and to enable root access for system "neo" on the tank/home file system:

# zfs set sharenfs='rw=@[::1],root=neo' tank/home

If you are using DNS for host name resolution, specify the fully-qualified hostname.

The following example shows how to set permissions so that user cindys can create, destroy, mount, and take snapshots on tank/cindys. The permissions on tank/cindys are also displayed.

# zfs allow ,destroy,mount,snapshot tank/cindys
# zfs allow tank/cindys
---- Permissions on tank/cindys --------------------------------------
Local+Descendent permissions:
        user cindys create,destroy,mount,snapshot

Because the tank/cindys mount point permission is set to 755 by default, user cindys will be unable to mount file systems under tank/cindys. Add an ACE similar to the following syntax to provide mount point access:

# chmod A+user:cindys:add_subdirectory:allow /tank/cindys

The following example shows how to grant anyone in the group staff to create file systems in 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 tank/users are also displayed.

# zfs allow staff create,mount tank/users
# zfs allow -c destroy tank/users
# zfs allow tank/users
---- Permissions on tank/users ---------------------------------------
Permission sets:
Local+Descendent permissions:
        group staff create,mount

The following example shows how to define and grant a permission set on the tank/users file system. The permissions on tank/users are also displayed.

# 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

The following example shows to grant the ability to set quotas and reservations on the users/home file system. The permissions on users/home are also displayed.

# zfs allow cindys quota, 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
users/home/marks  quota     10G    local

The following example shows how to remove the snapshot permission from the staff group on the tank/users file system. The permissions on tank/users are also displayed.

# 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

The following example shows how to see what has changed between a prior snapshot of a ZFS dataset and its current state. The -F option is used to indicate type information for the files affected.

# 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

The following example creates a bookmark to a snapshot. This bookmark can then be used instead of a snapshot in send streams.

# zfs bookmark rpool@snapshot rpool#bookmark

Property Options on a ZFS File System

The following example show how to share SMB filesystem through ZFS. Note that a user and their password must be given.

# smbmount // /mnt/tmp -o user=workgroup/turbo,password=obrut,uid=1000

Minimal /etc/samba/smb.conf configuration is required, as follows.

Samba will need to bind to the loopback interface for the ZFS utilities to communicate with Samba. This is the default behavior for most Linux distributions.

Samba must be able to authenticate a user. This can be done in a number of ways (passwd(5), LDAP, smbpasswd(5), &c.). How to do this is outside the scope of this document – refer to smb.conf(5) for more information.

See the USERSHARES section for all configuration options, in case you need to modify any options of the share afterwards. Do note that any changes done with the net(8) command will be undone if the share is ever unshared (like via a reboot).

Use ANSI color in zfs diff and zfs list output.
Cause zfs mount to use mount(8) to mount ZFS datasets. This option is provided for backwards compatibility with older ZFS versions.
Tells zfs to set the maximum pipe size for sends/recieves. Disabled by default on Linux due to an unfixed deadlock in Linux's pipe size handling code.
Time, in seconds, to wait for /dev/zfs to appear. Defaults to , max (10 minutes). If <0, wait forever; if 0, don't wait.


attr(1), gzip(1), ssh(1), chmod(2), fsync(2), stat(2), write(2), acl(5), attributes(5), exports(5), zfsconcepts(7), zfsprops(7), exportfs(8), mount(8), net(8), selinux(8), zfs-allow(8), zfs-bookmark(8), zfs-change-key(8), zfs-clone(8), zfs-create(8), zfs-destroy(8), zfs-diff(8), zfs-get(8), zfs-groupspace(8), zfs-hold(8), zfs-inherit(8), zfs-jail(8), zfs-list(8), zfs-load-key(8), zfs-mount(8), zfs-program(8), zfs-project(8), zfs-projectspace(8), zfs-promote(8), zfs-receive(8), zfs-redact(8), zfs-release(8), zfs-rename(8), zfs-rollback(8), zfs-send(8), zfs-set(8), zfs-share(8), zfs-snapshot(8), zfs-unallow(8), zfs-unjail(8), zfs-unload-key(8), zfs-unmount(8), zfs-upgrade(8), zfs-userspace(8), zfs-wait(8), zpool(8)

May 12, 2022 Debian