zfs/man/man8/zpool-scrub.8

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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
Distributed Spare (dRAID) Feature This patch adds a new top-level vdev type called dRAID, which stands for Distributed parity RAID. This pool configuration allows all dRAID vdevs to participate when rebuilding to a distributed hot spare device. This can substantially reduce the total time required to restore full parity to pool with a failed device. A dRAID pool can be created using the new top-level `draid` type. Like `raidz`, the desired redundancy is specified after the type: `draid[1,2,3]`. No additional information is required to create the pool and reasonable default values will be chosen based on the number of child vdevs in the dRAID vdev. zpool create <pool> draid[1,2,3] <vdevs...> Unlike raidz, additional optional dRAID configuration values can be provided as part of the draid type as colon separated values. This allows administrators to fully specify a layout for either performance or capacity reasons. The supported options include: zpool create <pool> \ draid[<parity>][:<data>d][:<children>c][:<spares>s] \ <vdevs...> - draid[parity] - Parity level (default 1) - draid[:<data>d] - Data devices per group (default 8) - draid[:<children>c] - Expected number of child vdevs - draid[:<spares>s] - Distributed hot spares (default 0) Abbreviated example `zpool status` output for a 68 disk dRAID pool with two distributed spares using special allocation classes. ``` pool: tank state: ONLINE config: NAME STATE READ WRITE CKSUM slag7 ONLINE 0 0 0 draid2:8d:68c:2s-0 ONLINE 0 0 0 L0 ONLINE 0 0 0 L1 ONLINE 0 0 0 ... U25 ONLINE 0 0 0 U26 ONLINE 0 0 0 spare-53 ONLINE 0 0 0 U27 ONLINE 0 0 0 draid2-0-0 ONLINE 0 0 0 U28 ONLINE 0 0 0 U29 ONLINE 0 0 0 ... U42 ONLINE 0 0 0 U43 ONLINE 0 0 0 special mirror-1 ONLINE 0 0 0 L5 ONLINE 0 0 0 U5 ONLINE 0 0 0 mirror-2 ONLINE 0 0 0 L6 ONLINE 0 0 0 U6 ONLINE 0 0 0 spares draid2-0-0 INUSE currently in use draid2-0-1 AVAIL ``` When adding test coverage for the new dRAID vdev type the following options were added to the ztest command. These options are leverages by zloop.sh to test a wide range of dRAID configurations. -K draid|raidz|random - kind of RAID to test -D <value> - dRAID data drives per group -S <value> - dRAID distributed hot spares -R <value> - RAID parity (raidz or dRAID) The zpool_create, zpool_import, redundancy, replacement and fault test groups have all been updated provide test coverage for the dRAID feature. Co-authored-by: Isaac Huang <he.huang@intel.com> Co-authored-by: Mark Maybee <mmaybee@cray.com> Co-authored-by: Don Brady <don.brady@delphix.com> Co-authored-by: Matthew Ahrens <mahrens@delphix.com> Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Mark Maybee <mmaybee@cray.com> Reviewed-by: Matt Ahrens <matt@delphix.com> Reviewed-by: Tony Hutter <hutter2@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #10102
2020-11-13 21:51:51 +00:00
.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
.Bl -tag -width "Exam"
.It Sy Example 1 : Status of pool with ongoing scrub:
Output:
.Bd -literal -compact -offset Ds
.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
Where:
.Bl -dash -offset indent
.It
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.
.El
.El
.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