BTRFS-SELECT-SUPER(8)                                         BTRFS                                         BTRFS-SELECT-SUPER(8)

NAME
       btrfs-select-super - overwrite primary superblock with a backup copy

SYNOPSIS
       btrfs-select-super -s number <device>

DESCRIPTION
       Destructively overwrite all copies of the superblock with a specified copy.  This helps in certain cases, for example when
       write  barriers were disabled during a power failure and not all superblocks were written, or if the primary superblock is
       damaged, e.g. accidentally overwritten.

       The filesystem specified by device must not be mounted.

       NOTE:
          Prior to overwriting the primary superblock, please make sure that the backup copies are valid!

       To dump a superblock use the btrfs inspect-internal dump-super command.

       Then run the check (in the non-repair mode) using the command btrfs check -s where -s specifies  the  superblock  copy  to
       use.

       Superblock copies exist in the following offsets on the device:

       • primary: 64KiB (65536)

       • 1st copy: 64MiB (67108864)

       • 2nd copy: 256GiB (274877906944)

       A superblock size is 4KiB (4096).

OPTIONS
       -s|--super <N>
              use Nth superblock copy, valid values are 0 1 or 2 if the respective superblock offset is within the device size

SEE ALSO
       btrfs(8)

6.6.3                                                      Mar 31, 2024                                     BTRFS-SELECT-SUPER(8)