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
The filesystem specified by device must not be mounted.
NotePrior to overwriting the primary superblock, please make surethat the backup copies are valid!
To dump a superblock use the btrfs inspect-internal dump-super
command, or the obsolete command btrfs-show-super.
Then run the check (in the non-repair mode) using the command btrfscheck -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).
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Btrfs v4.6.1 07/16/2016 BTRFS-SELECT-SUPER(8)