Martin Matuska bb2d13b686 zfs: merge openzfs/zfs@59493b63c (master)
Notable upstream pull request merges:
  #13782 Fix setting the large_block feature after receiving a snapshot
  #14157 FreeBSD: stop using buffer cache-only routines on sync
  #14172 zed: post a udev change event from spa_vdev_attach()
  #14181 zed: unclean disk attachment faults the vdev
  #14190 Bump checksum error counter before reporting to ZED
  #14196 Remove atomics from zh_refcount
  #14197 Don't leak packed recieved proprties
  #14198 Switch dnode stats to wmsums
  #14199 Remove few pointer dereferences in dbuf_read()
  #14200 Micro-optimize zrl_remove()
  #14204 Lua: Fix bad bitshift in lua_strx2number()
  #14212 Zstd fixes
  #14218 Avoid a null pointer dereference in zfs_mount() on FreeBSD
  #14235 nopwrites on dmu_sync-ed blocks can result in a panic
  #14236 zio can deadlock during device removal
  #14247 Micro-optimize fletcher4 calculations
  #14261 FreeBSD: zfs_register_callbacks() must implement error check
         correctly

Obtained from:	OpenZFS
OpenZFS commit:	59493b63c18ea223857066218d6a58b67eb88159
2022-12-07 14:10:46 +01:00

141 lines
4.1 KiB
Groff

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.\" Copyright (c) 2012, 2018 by Delphix. All rights reserved.
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.Dd July 25, 2021
.Dt ZPOOL-SCRUB 8
.Os
.
.Sh NAME
.Nm zpool-scrub
.Nd begin or resume scrub of ZFS storage pools
.Sh SYNOPSIS
.Nm zpool
.Cm scrub
.Op Fl s Ns | Ns Fl p
.Op Fl w
.Ar pool Ns
.
.Sh DESCRIPTION
Begins a scrub or resumes a paused scrub.
The scrub examines all data in the specified pools to verify that it checksums
correctly.
For replicated
.Pq mirror, raidz, or draid
devices, ZFS automatically repairs any damage discovered during the scrub.
The
.Nm zpool Cm status
command reports the progress of the scrub and summarizes the results of the
scrub upon completion.
.Pp
Scrubbing and resilvering are very similar operations.
The difference is that resilvering only examines data that ZFS knows to be out
of date
.Po
for example, when attaching a new device to a mirror or replacing an existing
device
.Pc ,
whereas scrubbing examines all data to discover silent errors due to hardware
faults or disk failure.
.Pp
Because scrubbing and resilvering are I/O-intensive operations, ZFS only allows
one at a time.
.Pp
A scrub is split into two parts: metadata scanning and block scrubbing.
The metadata scanning sorts blocks into large sequential ranges which can then
be read much more efficiently from disk when issuing the scrub I/O.
.Pp
If a scrub is paused, the
.Nm zpool Cm scrub
resumes it.
If a resilver is in progress, ZFS does not allow a scrub to be started until the
resilver completes.
.Pp
Note that, due to changes in pool data on a live system, it is possible for
scrubs to progress slightly beyond 100% completion.
During this period, no completion time estimate will be provided.
.
.Sh OPTIONS
.Bl -tag -width "-s"
.It Fl s
Stop scrubbing.
.It Fl p
Pause scrubbing.
Scrub pause state and progress are periodically synced to disk.
If the system is restarted or pool is exported during a paused scrub,
even after import, scrub will remain paused until it is resumed.
Once resumed the scrub will pick up from the place where it was last
checkpointed to disk.
To resume a paused scrub issue
.Nm zpool Cm scrub
again.
.It Fl w
Wait until scrub has completed before returning.
.El
.Sh EXAMPLES
.Ss Example 1
Status of pool with ongoing scrub:
.sp
.Bd -literal -compact
.No # Nm zpool Cm status
...
scan: scrub in progress since Sun Jul 25 16:07:49 2021
403M scanned at 100M/s, 68.4M issued at 10.0M/s, 405M total
0B repaired, 16.91% done, 00:00:04 to go
...
.Ed
.Pp
Where metadata which references 403M of file data has been
scanned at 100M/s, and 68.4M of that file data has been
scrubbed sequentially at 10.0M/s.
.Sh PERIODIC SCRUB
On machines using systemd, scrub timers can be enabled on per-pool basis.
.Nm weekly
and
.Nm monthly
timer units are provided.
.Bl -tag -width Ds
.It Xo
.Xc
.Nm systemctl
.Cm enable
.Cm zfs-scrub-\fIweekly\fB@\fIrpool\fB.timer
.Cm --now
.It Xo
.Xc
.Nm systemctl
.Cm enable
.Cm zfs-scrub-\fImonthly\fB@\fIotherpool\fB.timer
.Cm --now
.El
.
.Sh SEE ALSO
.Xr systemd.timer 5 ,
.Xr zpool-iostat 8 ,
.Xr zpool-resilver 8 ,
.Xr zpool-status 8