From 3d69435ee3292b4b1db2d61c4784789d75883821 Mon Sep 17 00:00:00 2001 From: Dimitri John Ledkov Date: Tue, 26 Jul 2016 13:24:39 +0100 Subject: Imported Upstream version 4.6.1 --- Documentation/btrfs-select-super.asciidoc | 47 +++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 Documentation/btrfs-select-super.asciidoc (limited to 'Documentation/btrfs-select-super.asciidoc') diff --git a/Documentation/btrfs-select-super.asciidoc b/Documentation/btrfs-select-super.asciidoc new file mode 100644 index 00000000..6e94a034 --- /dev/null +++ b/Documentation/btrfs-select-super.asciidoc @@ -0,0 +1,47 @@ +btrfs-select-super(8) +===================== + +NAME +---- +btrfs-select-super - overwrite primary superblock with a backup copy + +SYNOPSIS +-------- +*btrfs-select-super* -s number + +DESCRIPTION +----------- +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). + +OPTIONS +------- +-s|--super :: +use 'superblock'th superblock copy, valid values are 0 1 or 2 if the +respective superblock offset is within the device size + +SEE ALSO +-------- +`btrfs-inspect-internal`(8), +`btrfsck check`(8) -- cgit v1.2.3