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+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, eg. 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, or the obsolete command *btrfs-show-super*.
+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 <superblock>::
+use 'superblock'th superblock copy, valid values are 0 1 or 2 if the
+respective superblock offset is within the device size
+`btrfsck check`(8)