xref: /freebsd-src/sys/contrib/openzfs/man/man8/zfs-snapshot.8 (revision e2257b3168fc1697518265527e5d817eca6c43b8)

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.\" Copyright (c) 2009 Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 2011 Joshua M. Clulow <josh@sysmgr.org>
.\" Copyright (c) 2011, 2019 by Delphix. All rights reserved.
.\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
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.Dd March 16, 2022
.Dt ZFS-SNAPSHOT 8
.Os
.
.Sh NAME
.Nm zfs-snapshot
.Nd create snapshots of ZFS datasets
.Sh SYNOPSIS
.Nm zfs
.Cm snapshot
.Op Fl r
.Oo Fl o Ar property Ns = Ns Ar value Oc Ns …
.Ar dataset Ns @ Ns Ar snapname Ns …
.
.Sh DESCRIPTION
Creates a snapshot of a dataset or multiple snapshots of different
datasets.
.Pp
Snapshots are created atomically.
That is, a snapshot is a consistent image of a dataset at a specific
point in time; it includes all modifications to the dataset made by
system calls that have successfully completed before that point in time.
Recursive snapshots created through the
.Fl r
option are all created at the same time.
.Pp
.Nm zfs Cm snap
can be used as an alias for
.Nm zfs Cm snapshot .
.Pp
See the
.Sx Snapshots
section of
.Xr zfsconcepts 7
for details.
.Bl -tag -width "-o"
.It Fl o Ar property Ns = Ns Ar value
Set the specified property; see
.Nm zfs Cm create
for details.
.It Fl r
Recursively create snapshots of all descendent datasets
.El
.
.Sh EXAMPLES
.\" These are, respectively, examples 2, 3, 10, 15 from zfs.8
.\" Make sure to update them bidirectionally
.Ss Example 1 : No Creating a ZFS Snapshot
The following command creates a snapshot named
.Ar yesterday .
This snapshot is mounted on demand in the
.Pa .zfs/snapshot
directory at the root of the
.Ar pool/home/bob
file system.
.Dl # Nm zfs Cm snapshot Ar pool/home/bob Ns @ Ns Ar yesterday
.
.Ss Example 2 : No Creating and Destroying Multiple Snapshots
The following command creates snapshots named
.Ar yesterday No of Ar pool/home
and all of its descendent file systems.
Each snapshot is mounted on demand in the
.Pa .zfs/snapshot
directory at the root of its file system.
The second command destroys the newly created snapshots.
.Dl # Nm zfs Cm snapshot Fl r Ar pool/home Ns @ Ns Ar yesterday
.Dl # Nm zfs Cm destroy Fl r Ar pool/home Ns @ Ns Ar yesterday
.
.Ss Example 3 : 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:
.Bd -literal -compact -offset Ds
.No # Nm zfs Cm create Ar pool/project/production
  populate /pool/project/production with data
.No # Nm zfs Cm snapshot Ar pool/project/production Ns @ Ns Ar today
.No # Nm zfs Cm clone Ar pool/project/production@today pool/project/beta
  make changes to /pool/project/beta and test them
.No # Nm zfs Cm promote Ar pool/project/beta
.No # Nm zfs Cm rename Ar pool/project/production pool/project/legacy
.No # Nm zfs Cm rename Ar pool/project/beta pool/project/production
  once the legacy version is no longer needed, it can be destroyed
.No # Nm zfs Cm destroy Ar pool/project/legacy
.Ed
.
.Ss Example 4 : 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:
.Bd -literal -compact -offset Ds
.No # Nm zfs Cm destroy Fl r Ar pool/users@7daysago
.No # Nm zfs Cm rename Fl r Ar pool/users@6daysago No @ Ns Ar 7daysago
.No # Nm zfs Cm rename Fl r Ar pool/users@5daysago No @ Ns Ar 6daysago
.No # Nm zfs Cm rename Fl r Ar pool/users@4daysago No @ Ns Ar 5daysago
.No # Nm zfs Cm rename Fl r Ar pool/users@3daysago No @ Ns Ar 4daysago
.No # Nm zfs Cm rename Fl r Ar pool/users@2daysago No @ Ns Ar 3daysago
.No # Nm zfs Cm rename Fl r Ar pool/users@yesterday No @ Ns Ar 2daysago
.No # Nm zfs Cm rename Fl r Ar pool/users@today No @ Ns Ar yesterday
.No # Nm zfs Cm snapshot Fl r Ar pool/users Ns @ Ns Ar today
.Ed
.
.Sh SEE ALSO
.Xr zfs-bookmark 8 ,
.Xr zfs-clone 8 ,
.Xr zfs-destroy 8 ,
.Xr zfs-diff 8 ,
.Xr zfs-hold 8 ,
.Xr zfs-rename 8 ,
.Xr zfs-rollback 8 ,
.Xr zfs-send 8