btrfs-select-super - overwrite primary superblock with a backup copy
btrfs-select-super -s number <device>
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.
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).
- -s|--super <N>
- use Nth superblock copy, valid values are 0 1 or 2 if the respective superblock offset is within the device size
|November 15, 2023||6.6.2|