1BTRFS-SELECT-SUPER(8)            Btrfs Manual            BTRFS-SELECT-SUPER(8)
2
3
4

NAME

6       btrfs-select-super - overwrite primary superblock with a backup copy
7

SYNOPSIS

9       btrfs-select-super -s number <device>
10

DESCRIPTION

12       Destructively overwrite all copies of the superblock with a specified
13       copy. This helps in certain cases, for example when write barriers were
14       disabled during a power failure and not all superblocks were written,
15       or if the primary superblock is damaged, eg. accidentally overwritten.
16
17       The filesystem specified by device must not be mounted.
18
19           Note
20           Prior to overwriting the primary superblock, please make sure that
21           the backup copies are valid!
22
23       To dump a superblock use the btrfs inspect-internal dump-super command.
24
25       Then run the check (in the non-repair mode) using the command btrfs
26       check -s where -s specifies the superblock copy to use.
27
28       Superblock copies exist in the following offsets on the device:
29
30       ·   primary: 64KiB (65536)
31
32       ·   1st copy: 64MiB (67108864)
33
34       ·   2nd copy: 256GiB (274877906944)
35
36       A superblock size is 4KiB (4096).
37

OPTIONS

39       -s|--super <superblock>
40           use 'superblock’th superblock copy, valid values are 0 1 or 2 if
41           the respective superblock offset is within the device size
42

SEE ALSO

44       btrfs-inspect-internal(8), btrfsck check(8)
45
46
47
48Btrfs v5.4                        12/03/2019             BTRFS-SELECT-SUPER(8)
Impressum