ZFS(8)

📦
version 2.4.4 · 9 versions
, in alpine 3.23, alpine 3.24, nixos 26.05, nixpkgs unstable, ubuntu resolute, ubuntu stonking

💖 ZFS(8) — the zfs girlies' guide 💖

System Manager's Manual ✨ like, the whole manual, but make it make sense

🌸 NAME 🌸

zfs — configure ZFS datasets. that's it, that's the vibe. she configures. datasets. slay. 💅

✨ SYNOPSIS ✨

zfs -?V
zfs version [-j]
zfs subcommand [arguments]

🦋 DESCRIPTION 🦋

okay so bestie, listen. the zfs command is the one that configures ZFS datasets inside a ZFS storage pool — and like, the pool stuff itself lives over in zpool(8), we don't do that here. a dataset is identified by a unique path inside the ZFS namespace, and it looks like this:

pool[/component]/component

for example:

rpool/var/log

and now the ✨rules✨ because there are always rules:

  • the maximum length of a dataset name is ZFS_MAX_DATASET_NAME_LEN - 1 ASCII characters (currently 255) and it has to satisfy [A-Za-z_.:/ -]. yes, that's the whole character buffet.
  • snapshots are allowed to contain a single @ character 🎀
  • bookmarks are allowed to contain a single # character
  • / is used as the separator between components
  • the maximum amount of nesting allowed in a path is zfs_max_dataset_nesting levels deep. don't push her.
  • ZFS tunables (zfs_*) are explained in zfs(4), go look if you're nosy (affectionate).

a dataset can be one of these four things, and honestly? iconic lineup:

  • 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. so like, applications that depend on standards conformance might fail due to non-standard behavior when checking file system free space. not her fault, just the lore. 💀
  • 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. so like, don't be dramatic and use a volume when you don't need one.
  • 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. a little time capsule, a little freeze-frame. 📸
  • 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, if you want the deep lore. 🌈

💜 Properties 💜

properties come in two flavors: native properties and user-defined (or "user") properties. native properties either export internal statistics or control ZFS behavior. plus, native properties are either editable or read-only. user properties have no effect on ZFS behavior at all — but you can use them to annotate datasets in a way that's meaningful in your environment. cute little sticky notes. 🍓

for more info 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. yes bestie, all of it. for an overview of encryption, see zfs-load-key(8). 🫶

👑 SUBCOMMANDS 👑

heads up: all subcommands that modify state are logged persistently to the pool in their original form. so like, the pool remembers. forever. no cap.
  • zfs -? — displays a help message. the classic cry for help, but helpful.
  • zfs -V, --version
  • zfs version [-j] — displays the software version of the zfs userland utility and the zfs kernel module. use the -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. so like, she's held, okay?
  • 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. glow up moment. ✨

📤 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. mysterious. love that for her. 🕶️

💜 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 📊

🗂️ 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. yes, Lua. she contains multitudes. 💅

✍️ Data rewrite ✍️

🚔 Jails 🚔

⏳ Waiting ⏳

  • zfs-wait(8) — wait for background activity in a filesystem to complete. the "girl just give it a sec" subcommand. 🫶

🚦 EXIT STATUS 🚦

the zfs utility exits 0 on success, 1 if an error occurs, and 2 if invalid command line options were specified. three moods. that's the whole emotional spectrum. 😭

🌟 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. so like, the baby gets the parent's whole setup for free. generational wealth. 👑

# 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. create then destroy, the full circle of life. 💀

# 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 💖

okay bestie, this one is the ~big reveal~ — every single property on pool/home/bob, all at once. Run this and it's giving full inventory, no cap:

# 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                      -

look at all those defaults and locals and little -s — that last column is literally the receipts for where each value came from. 👑

and if you only want one lil value? grab it like this:

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

just on. that's it. that's the whole meal. ✨

and if you wanna see only the stuff that was set locally (as in, not inherited from anyone), bestie, say less:

# 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

two rows. iconic. the way -s local just filters out all the inherited noise?? obsessed. 💅

Example 8: Rolling Back a ZFS File System 🌈

say you fumbled and need to go back to how things were. this command rewinds the contents of pool/home/anne back to the snapshot named yesterday, and — heads up — it deletes all intermediate snapshots on the way. gone. poof.

# zfs rollback -r pool/home/anne@yesterday
the -r is the "and also nuke everything between here and there" flag. very main character, very destructive. know that before you hit enter, fr fr. 😭

Example 9: Creating a ZFS Clone 🦋

a clone is a writable file system that starts out with the same contents as a snapshot. watch:

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

now pool/clone is a whole writable vibe that started life as pool/home/bob@yesterday. cute. 🎀

Example 10: Promoting a ZFS Clone 💜

okay this one is the ✨plot twist✨ example. you wanna test some changes on a copy, then swap it in for the original like nothing happened. clones + promotion + renaming, all together:

# 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

read that again, bestie — you make a clone, you test your lil changes on it, you promote it so it becomes the real one, you rename the old one out of the way to legacy, you rename the beta into the production slot, and then once legacy is just sitting there collecting dust you destroy it. chef's kiss. the glow-up was real. 🌟

Example 11: Inheriting ZFS Properties 🍓

want a dataset to stop being special and just take after its parent? say less:

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

boom — pool/home/bob and pool/home/anne now inherit the checksum property from their parent. generational. 🫶

Example 12: Remotely Replicating ZFS Data 🌸

sending your data to another machine across the internet?? long-distance relationship energy, but make it storage. here you send a full stream first, then an incremental one:

# 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 full stream lands as poolB/received/fs@a, and the incremental stream lands as poolB/received/fs@b. important deets: poolB has to already contain the file system poolB/received, and it must not already contain poolB/received/fs at the start. no pre-existing copies, bestie. ✨

Example 13: Using the zfs receive -d Option 🎀

this is the -d slay. you send poolA/fsA/fsB@snap off to a remote machine, and it gets received into poolB/received/fsA/fsB@snap. the fsA/fsB@snap part of the new name? it's literally derived from the name of the snapshot you sent. mind. blown.

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

rules of the game: poolB must already contain the file system poolB/received. and if poolB/received/fsA doesn't exist yet? it just gets created as an empty file system. no complaints, no drama. 💅

Example 14: Setting User Properties 💖

you can make up your OWN properties, bestie. user-defined, your rules. this one sets com.example:department on a dataset:

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

custom property, custom lore. 🏷️

Example 15: Performing a Rolling Snapshot 🌈

this is the "keep a tidy rotation going" example — a whole week's worth of snapshots with a consistent naming scheme. the move is: destroy the oldest, rename the rest down the line, then make a fresh one. like a lil conveyor belt:

# 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

see how everything shuffles down by one and @today becomes the new baby at the top? it's giving organized. it's giving consistent. it's giving no notes. 😌

Example 16: Setting sharenfs Property Options on a ZFS File System 🦋

wanna share a file system over NFS with specific rules? watch this — it enables read-write access for a set of IP addresses and enables root access for a system named neo on tank/home:

# zfs set sharenfs='rw=@123.123.0.0/16:[::1],root=neo' tank/home
pro tip from the page itself, no cap: if you're using DNS for host name resolution, specify the fully-qualified hostname. don't be vague about it, bestie. 💅

Example 17: Delegating ZFS Administration Permissions on a ZFS Dataset 👑

okay so you don't have to do EVERYTHING yourself — you can hand out powers. this sets it up so user cindys can create, destroy, mount, and take snapshots on tank/cindys:

# 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

and then the lil plot twist 🫠 — 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. rude, honestly. to fix it, add an ACE like this to give mount point access:

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

fixed. slay. 💖

Example 18: Delegating Create Time Permissions on a ZFS Dataset ✨

this one lets anyone in the group staff create file systems in tank/users. and the cute part? this syntax also lets staff members destroy their own file systems — but not anyone else's. boundaries, bestie. we love them:

# 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

see the -c? that's what makes destroy a create-time permission. so the destroy power only applies to stuff they make themselves. fair and balanced. ⚖️

Example 19: Defining and Granting a Permission Set on a ZFS Dataset 🎀

why type out a whole list of permissions every time when you can bundle them into a named set? define once, grant everywhere:

# 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

@pset is the lil permission bundle, and staff just gets handed the whole thing. efficiency queen behavior. 👑

Example 20: Delegating Property Permissions on a ZFS Dataset 🌸

this one grants the ability to set quota and reservation on the users/home file system. so cindys can manage her own space without needing the big boss:

# 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

see how cindys% (that's her, doing her own thing) sets a quota and then reads it right back? and SOURCE says local because she set it. autonomy. we stan. 🫶

Example 21: Removing ZFS Delegated Permissions on a ZFS Dataset 💅

sometimes you gotta take the power back. this removes the snapshot permission from the staff group on the tank/users file system:

# 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

notice how staff still has @pset — the direct snapshot grant is what got yanked. and @pset still holds its own create,destroy,mount,snapshot, so read carefully, bestie. unallow targets exactly what you point it at. no more, no less. 💜

💖 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 shows how to share an 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).

💖 And that's a wrap, bestie! This page is brought to you by OpenZFS and it's dated May 12, 2025. Slay. 💅✨
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