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)