xfs_check(8)                                                                                                        xfs_check(8)



NAME
       xfs_check - check XFS filesystem consistency

SYNOPSIS
       xfs_check [ -i ino ] ... [ -b bno ] ... [ -f ] [ -s ] [ -v ] [ -l logdev ] device

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 device 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 normally be unmounted or read-only during the execution of xfs_check.  Otherwise, spurious problems are
       reported.

OPTIONS
       -f     Specifies  that the filesystem image to be processed is stored in a regular file at device (see the mkfs.xfs(8) -d
              file option). This might happen if an image copy of a filesystem has been made into an ordinary file.

       -l logdev
              Specifies the device where the filesystem's external log resides.  Only for those filesystems which use an  exter-
              nal log. See the mkfs.xfs(8) -l option, and refer to xfs(5) for a detailed description of the XFS log.

       -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 the specified inode ino.  For instance, it can be used to  locate  all  the  blocks
              associated with a given inode.

       -b bno Specifies  verbose  behavior  for the specific filesystem block at bno.  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(8)) and file system blocks may be accomplished using xfs_db(8)'s
              convert command.

       Any output that is produced when xfs_check is not run in verbose mode indicates 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 the filesystem, make a new filesystem, then use xfsrestore(8)  to  restore  the  data  onto  the  new
       filesystem.  Note that xfsdump may fail on a corrupt filesystem.  However, 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
       If the filesystem is completely corrupt, a core dump might be produced instead of the message
              device 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 message
              out of memory
       is printed.

       The following is a description of the most likely problems and the associated messages.  Most of the diagnostics produced
       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 multiple inodes.  This message usually follows a message of the next type.

       block a/b expected type unknown got y
              The block is used multiple times (shared).

       block a/b type unknown not expected
              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 references 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).



                                                                                                                    xfs_check(8)