ZFS(8) FreeBSD System Manager's Manual ZFS(8)
NAME
zfs - configure ZFS datasets
SYNOPSIS
zfs -?V
zfs version [-j]
zfs subcommand [arguments]
DESCRIPTION
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:
pool[/component]/component
for example:
rpool/var/log
The maximum length of a dataset name is ZFS_MAX_DATASET_NAME_LEN - 1
ASCII characters (currently 255) satisfying [A-Za-z_.:/ -]. 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
zfs_max_dataset_nesting levels deep. ZFS tunables (zfs_*) are explained
in zfs(4).
A dataset can be one of the following:
file system 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.
volume 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.
snapshot 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.
bookmark 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
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).
Encryption
Enabling the encryption 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
userused/groupused/projectused data. For an overview of encryption, see
zfs-load-key(8).
SUBCOMMANDS
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 [-j]
Displays the software version of the zfs userland utility and the zfs
kernel module. Use -j option to output in JSON format.
Dataset Management
zfs-list(8)
Lists the property information for the given datasets in tabular form.
zfs-create(8)
Creates a new ZFS file system or volume.
zfs-destroy(8)
Destroys the given dataset(s), snapshot(s), or bookmark.
zfs-rename(8)
Renames the given dataset (filesystem or snapshot).
zfs-upgrade(8)
Manage upgrading the on-disk version of filesystems.
Snapshots
zfs-snapshot(8)
Creates snapshots with the given names.
zfs-rollback(8)
Roll back the given dataset to a previous snapshot.
zfs-hold(8)/zfs-release(8)
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 EBUSY.
zfs-diff(8)
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.
Clones
zfs-clone(8)
Creates a clone of the given snapshot.
zfs-promote(8)
Promotes a clone file system to no longer be dependent on its "origin"
snapshot.
Send & Receive
zfs-send(8)
Generate a send stream, which may be of a filesystem, and may be
incremental from a bookmark.
zfs-receive(8)
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.
zfs-bookmark(8)
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.
zfs-redact(8)
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.
Properties
zfs-get(8)
Displays properties for the given datasets.
zfs-set(8)
Sets the property or list of properties to the given value(s) for each
dataset.
zfs-inherit(8)
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.
Quotas
zfs-userspace(8)/zfs-groupspace(8)/zfs-projectspace(8)
Displays space consumed by, and quotas on, each user, group, or project
in the specified filesystem or snapshot.
zfs-project(8)
List, set, or clear project ID and/or inherit flag on the files or
directories.
Mountpoints
zfs-mount(8)
Displays all ZFS file systems currently mounted, or mount ZFS
filesystem on a path described by its mountpoint property.
zfs-unmount(8)
Unmounts currently mounted ZFS file systems.
Shares
zfs-share(8)
Shares available ZFS file systems.
zfs-unshare(8)
Unshares currently shared ZFS file systems.
Delegated Administration
zfs-allow(8)
Delegate permissions on the specified filesystem or volume.
zfs-unallow(8)
Remove delegated permissions on the specified filesystem or volume.
Encryption
zfs-change-key(8)
Add or change an encryption key on the specified dataset.
zfs-load-key(8)
Load the key for the specified encrypted dataset, enabling access.
zfs-unload-key(8)
Unload a key for the specified dataset, removing the ability to access
the dataset.
Channel Programs
zfs-program(8)
Execute ZFS administrative operations programmatically via a Lua
script-language channel program.
Data rewrite
zfs-rewrite(8)
Rewrite specified files without modification.
Jails
zfs-jail(8)
Attaches a filesystem to a jail.
zfs-unjail(8)
Detaches a filesystem from a jail.
Waiting
zfs-wait(8)
Wait for background activity in a filesystem to complete.
EXIT STATUS
The zfs utility exits 0 on success, 1 if an error occurs, and 2 if
invalid command line options were specified.
EXAMPLES
Example 1: Creating a ZFS File System Hierarchy
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
Example 2: Creating a ZFS Snapshot
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
Example 3: Creating and Destroying Multiple Snapshots
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
Example 4: Disabling and Enabling File System Compression
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
Example 5: Listing ZFS Datasets
The following command lists all active file systems and volumes in the
system. Snapshots are displayed if listsnaps=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
Example 6: Setting a Quota on a ZFS File System
The following command sets a quota of 50 Gbytes for pool/home/bob:
# zfs set quota=50G pool/home/bob
Example 7: Listing ZFS Properties
The following command lists all properties for pool/home/bob:
# 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 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
on
The following command lists all properties with local settings for
pool/home/bob:
# 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
Example 8: Rolling Back a ZFS File System
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
Example 9: Creating a ZFS Clone
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
Example 10: 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:
# 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
Example 11: Inheriting ZFS Properties
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
Example 12: Remotely Replicating ZFS Data
The following commands send a full stream and then an incremental stream
to a remote machine, restoring them into poolB/received/fs@a and
poolB/received/fs@b, respectively. poolB must contain the file system
poolB/received, and must not initially contain poolB/received/fs.
# 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
Example 13: Using the zfs receive -d Option
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
Example 14: Setting User Properties
The following example sets the user-defined com.example:department
property for a dataset:
# zfs set com.example:department=12345 tank/accounting
Example 15: 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:
# 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
Example 16: Setting sharenfs Property Options on a ZFS File System
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=@123.123.0.0/16:[::1],root=neo' tank/home
If you are using DNS for host name resolution, specify the fully-
qualified hostname.
Example 17: Delegating ZFS Administration Permissions on a ZFS Dataset
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 cindys create,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
Example 18: Delegating Create Time Permissions on a ZFS Dataset
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:
destroy
Local+Descendent permissions:
group staff create,mount
Example 19: Defining and Granting a Permission Set on a ZFS Dataset
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
Example 20: Delegating Property Permissions on a ZFS Dataset
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,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
Example 21: Removing ZFS Delegated Permissions on a ZFS Dataset
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
Example 22: 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 -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
Example 23: Creating a bookmark
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
Example 24: Setting sharesmb 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 //127.0.0.1/share_tmp /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).
ENVIRONMENT VARIABLES
ZFS_COLOR Use ANSI color in zfs diff and zfs list output.
ZFS_MOUNT_HELPER Cause zfs mount to use mount(8) to mount ZFS
datasets. This option is provided for backwards
compatibility with older ZFS versions.
ZFS_SET_PIPE_MAX Tells zfs to set the maximum pipe size for
sends/receives. Disabled by default on Linux due to
an unfixed deadlock in Linux's pipe size handling
code.
ZFS_MODULE_TIMEOUT Time, in seconds, to wait for /dev/zfs to appear.
Defaults to 10, max 600 (10 minutes). If <0, wait
forever; if 0, don't wait.
INTERFACE STABILITY
Committed.
SEE ALSO
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-unshare(8),
zfs-upgrade(8), zfs-userspace(8), zfs-wait(8), zpool(8)
FreeBSD 15.1-STABLE-HBSD May 12, 2025 ZFS(8)