xfs_check - check XFS filesystem consistency
SYNOPSIS
xfs_check [ -i ino ] ... [ -b bno ] ... [ -s ] [ -v ] xfs_special
xfs_check -f [ -i ino ] ... [ -b bno ] ... [ -s ] [ -v ] file
DESCRIPTION
xfs_check checks whether an XFS filesystem is consistent.
It is normally run only when there is reason to believe
that the filesystem has a consistency problem. The
filesystem to be checked is specified by the xfs_special
argument, which should be the disk or volume device for
the filesystem. Filesystems stored in files can also be
checked, using the -f flag. The filesystem should nor
mally be unmounted or read-only during the execution of
xfs_check. Otherwise, spurious problems are reported.
The options to xfs_check are:
-f Specifies that the special device is actually a
file (see the mkfs.xfs -d file option). This
might happen if an image copy of a filesystem has
been made into an ordinary file.
-s Specifies that only serious errors should be
reported. Serious errors are those that make it
impossible to find major data structures in the
filesystem. This option can be used to cut down
the amount of output when there is a serious
problem, when the output might make it difficult
to see what the real problem is.
-v Specifies verbose output; it is impossibly long
for a reasonably-sized filesystem. This option
is intended for internal use only.
-i ino Specifies verbose behavior for a specific inode.
For instance, it can be used to locate all the
blocks associated with a given inode.
-b bno Specifies verbose behavior for a specific
filesystem block. For instance, it can be used
to determine what a specific block is used for.
The block number is a "file system block number".
Conversion between disk addresses (i.e. addresses
reported by xfs_bmap) and file system blocks may
be accomplished using xfs_db's convert command.
Any non-verbose output from xfs_check means that the
filesystem has an inconsistency. The filesystem can be
repaired using either xfs_repair(8) to fix the filesystem
in place, or by using xfsdump(8) and mkfs.xfs(8) to dump
store(8) to restore the data onto the new filesystem.
Note that xfsdump may fail on a corrupt filesystem. How
ever, if the filesystem is mountable, xfsdump can be used
to try and save important data before repairing the
filesystem with xfs_repair. If the filesystem is not
mountable though, xfs_repair is the only viable option.
DIAGNOSTICS
Under one circumstance, xfs_check unfortunately might dump
core rather than produce useful output. If the filesystem
is completely corrupt, a core dump might be produced
instead of the message xxx is not a valid filesystem
If the filesystem is very large (has many files) then
xfs_check might run out of memory. In this case the mes
sage out of memory is printed.
The following is a description of the most likely problems
and the associated messages. Most of the diagnostics pro
duced are only meaningful with an understanding of the
structure of the filesystem.
agf_freeblks n, counted m in ag a
The freeblocks count in the allocation group header
for allocation group a doesn't match the number of
blocks counted free.
agf_longest n, counted m in ag a
The longest free extent in the allocation group
header for allocation group a doesn't match the
longest free extent found in the allocation group.
agi_count n, counted m in ag a
The allocated inode count in the allocation group
header for allocation group a doesn't match the
number of inodes counted in the allocation group.
agi_freecount n, counted m in ag a
The free inode count in the allocation group header
for allocation group a doesn't match the number of
inodes counted free in the allocation group.
block a/b expected inum 0 got i
The block number is specified as a pair (allocation
group number, block in the allocation group). The
block is used multiple times (shared), between mul
tiple inodes. This message usually follows a mes
sage of the next type.
block a/b expected type unknown got y
The block is used multiple times (shared).
The block is unaccounted for (not in the freelist
and not in use).
link count mismatch for inode nnn (name xxx), nlink m,
counted n
The inode has a bad link count (number of refer
ences in directories).
rtblock b expected inum 0 got i
The block is used multiple times (shared), between
multiple inodes. This message usually follows a
message of the next type.
rtblock b expected type unknown got y
The real-time block is used multiple times
(shared).
rtblock b type unknown not expected
The real-time block is unaccounted for (not in the
freelist and not in use).
sb_fdblocks n, counted m
The number of free data blocks recorded in the
superblock doesn't match the number counted free in
the filesystem.
sb_frextents n, counted m
The number of free real-time extents recorded in
the superblock doesn't match the number counted
free in the filesystem.
sb_icount n, counted m
The number of allocated inodes recorded in the
superblock doesn't match the number allocated in
the filesystem.
sb_ifree n, counted m
The number of free inodes recorded in the
superblock doesn't match the number free in the
filesystem.
SEE ALSO
mkfs.xfs(8), xfsdump(8), xfsrestore(8), xfs_ncheck(8),
xfs_repair(8), xfs(5).
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