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,  eg.
       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)

COPYRIGHT

       2022