BTRFS-SCRUB(8)                  Btrfs Manual                  BTRFS-SCRUB(8)

NAME         top

       btrfs-scrub - scrub btrfs filesystem, verify block checksums

SYNOPSIS         top

       btrfs scrub <subcommand> <args>

DESCRIPTION         top

       btrfs scrub is used to scrub a btrfs filesystem, which will read all
       data and metadata blocks from all devices and verify checksums.
       Automatically repair corrupted blocks if there’s a correct copy

           Scrub is not a filesystem checker (fsck) and does not verify nor
           repair structural damage in the filesystem.

       The user is supposed to run it manually or via a periodic system
       service. The recommended period is a month but could be less. The
       estimated device bandwidth utilization is about 80% on an idle
       filesystem. The IO priority class is by default idle so background
       scrub should not significantly interfere with normal filesystem

       The scrubbing status is recorded in /var/lib/btrfs/ in textual files
       named scrub.status.UUID for a filesystem identified by the given
       UUID. (Progress state is communicated through a named pipe in file
       scrub.progress.UUID in the same directory.) The status file is
       updated every 5 seconds. A resumed scrub will continue from the last
       saved position.

SUBCOMMAND         top

       cancel <path>|<device>
           If a scrub is running on the filesystem identified by path cancel

           If a device is specified, the corresponding filesystem is found
           and btrfs scrub cancel behaves as if it was called on that

       resume [-BdqrR] [-c <ioprio_class> -n <ioprio_classdata>]
           Resume a cancelled or interrupted scrub on the filesystem
           identified by path or on a given device.

           Does not start a new scrub if the last scrub finished


           see scrub start.

       start [-BdqrRf] [-c <ioprio_class> -n <ioprio_classdata>]
           Start a scrub on all devices of the filesystem identified by path
           or on a single device. If a scrub is already running, the new one

           Without options, scrub is started as a background process.

           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


               do not background and print scrub statistics when finished

               print separate statistics for each device of the filesystem
               (-B only) at the end

               be quiet, omit error messages and statistics

               run in read-only mode, do not attempt to correct anything,
               can be run on a read-only filesystem

               print raw statistics per-device instead of a summary

           -c <ioprio_class>
               set IO priority class (see ionice(1) manpage)

           -n <ioprio_classdata>
               set IO priority classdata (see ionice(1) manpage)

               force starting new scrub even if a scrub is already running,
               this can useful when scrub status file is damaged and reports
               a running scrub although it is not, but should not normally
               be necessary

       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
           cancelled scrub for that filesystem or device.


               print separate statistics for each device of the filesystem

EXIT STATUS         top

       btrfs scrub returns a zero exit status if it succeeds. Non zero is
       returned in case of failure:

           scrub couldn’t be performed

           there is nothing to resume

           scrub found uncorrectable errors

AVAILABILITY         top

       btrfs is part of btrfs-progs. Please refer to the btrfs wiki for further details.

SEE ALSO         top

       mkfs.btrfs(8), ionice(1)

COLOPHON         top

       This page is part of the btrfs-progs (btrfs filesystem tools)
       project.  Information about the project can be found at 
       If you have a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       on 2018-10-29.  (At that time, the date of the most recent commit
       that was found in the repository was 2018-08-06.)  If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail

Btrfs v4.6.1                     01/23/2018                   BTRFS-SCRUB(8)

Pages that refer to this page: btrfs(8)btrfs-check(8)btrfs-rescue(8)