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 respec-
tive superblock offset is within the device size
SEE ALSO
btrfs(8)
6.14 Apr 17, 2025 BTRFS-SELECT-SUPER(8)
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