btrfs-progs/Documentation/btrfs-scrub.txt

btrfs-scrub(8)
==============

NAME
----
btrfs-scrub - scrub btrfs filesystem

SYNOPSIS
--------
*btrfs scrub* <subcommand> <args>

DESCRIPTION
-----------
*btrfs scrub* is used to scrub a btrfs filesystem, which will reading all data
from all disks and verifying checksums.

SUBCOMMAND
----------
*start* [-BdqrRf] [-c <ioprio_class> -n <ioprio_classdata>] <path>|<device>::
Start a scrub on all devices of the filesystem identified by <path> or on
a single <device>.
+
Without options, scrub is started as a background process.
Progress can be obtained with the *scrub status* command. Scrubbing
involves reading all data from all disks and verifying checksums. Errors are
corrected along the way if possible.
+
The default IO priority of scrub is the idle class. The priority can be
configured similar to the `ionice`(1) syntax using '-c' and '-n' options.
+
`Options`
+
-B::::
Do not background and print scrub statistics when finished.
-d::::
Print separate statistics for each device of the filesystem (-B only).
-q::::
Quiet. Omit error messages and statistics.
-r::::
Read only mode. Do not attempt to correct anything.
-R::::
Raw print mode. Print full data instead of summary.
-c <ioprio_class>::::
Set IO priority class (see
 ionice (1)
manpage).
-n <ioprio_classdata>::::
Set IO priority classdata (see `ionice`(1) manpage).
-f::::
force to check whether scrub has started or resumed in userspace.
this is useful when scrub stat record file is damaged.

*cancel* <path>|<device>::
If a scrub is running on the filesystem identified by <path>, cancel it.
+
Progress is saved in the scrub progress file and scrubbing can be resumed later
using the scrub resume command.
If a <device> is given, the corresponding filesystem is found and
scrub cancel behaves as if it was called on that filesystem.

*resume* [-BdqrR] [-c <ioprio_class> -n <ioprio_classdata>] <path>|<device>::
Resume a canceled or interrupted scrub cycle on the filesystem identified by
<path> or on a given <device>.
+
Does not start a new scrub if the last scrub finished successfully.
+
`Options`
+
see *scrub start*.

*status* [-d] <path>|<device>::
Show status of a running scrub for the filesystem identified by <path> or
for the specified <device>.
+
If no scrub is running, show statistics of the last finished or canceled scrub
for that filesystem or device.
+
`Options`
+
-d::::
Print separate statistics for each device of the filesystem.

EXIT STATUS
-----------
*btrfs scrub* returns a zero exist status if it succeeds. Non zero is
returned in case of failure.

AVAILABILITY
------------
*btrfs* is part of btrfs-progs.
Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for
further details.

SEE ALSO
--------
`mkfs.btrfs`(8),