btrfs-select-super8
Overwrite primary superblock with a backup copy
Usage
btrfs-select-super -s
number
<device>
Overview
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
History
- Arch Linux 2026-11-01: the text shown here
- Debian 13 (Trixie)
- Debian 12 (Bookworm)
- Debian 11 (Bullseye)
- Debian 10 (Buster)
- Debian 9 (Stretch)