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xfs_repair(8)               System Manager's Manual              xfs_repair(8)

NAME
       xfs_repair - repair an XFS filesystem

SYNOPSIS
       xfs_repair  [  -dfLPv ] [ -n | -e ] [ -m maxmem ] [ -c subopt=value ] [
       -o subopt[=value] ] [ -t interval ] [ -l logdev ] [ -r rtdev ] device
       xfs_repair -V

DESCRIPTION
       xfs_repair repairs corrupt or damaged  XFS  filesystems  (see  xfs(5)).
       The  filesystem  is specified using the device argument which should be
       the device name of the disk partition or volume containing the filesys-
       tem.  If  given  the name of a block device, xfs_repair will attempt to
       find the raw device associated with the specified block device and will
       use the raw device instead.

       Regardless, the filesystem to be repaired must be unmounted, otherwise,
       the resulting filesystem may be inconsistent or corrupt.

OPTIONS
       -f     Specifies that the filesystem image to be processed is stored in
              a regular file at device (see the mkfs.xfs -d file option). This
              might happen if an image copy of a filesystem has been copied or
              written into an ordinary file.  This option implies that any ex-
              ternal log or realtime section is also in an ordinary file.

       -L     Force Log Zeroing.  Forces xfs_repair to zero the log even if it
              is  dirty  (contains  metadata changes).  When using this option
              the filesystem will likely appear to be corrupt, and  can  cause
              the  loss of user files and/or data.  See the DIRTY LOGS section
              for more information.

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

       -r rtdev
              Specifies  the  device special file where the filesystem's real-
              time section resides. Only for those filesystems which use a re-
              altime section.  See the mkfs.xfs -r option, and refer to xfs(5)
              for a detailed description of the XFS realtime section.

       -n     No modify mode. Specifies that xfs_repair should not modify  the
              filesystem but should only scan the filesystem and indicate what
              repairs would have been made. This option  cannot  be  used  to-
              gether with -e.

       -P     Disable  prefetching of inode and directory blocks. Use this op-
              tion if you find xfs_repair gets stuck and stops proceeding. In-
              terrupting a stuck xfs_repair is safe.

       -m maxmem
              Specifies   the   approximate   maximum  amount  of  memory,  in
              megabytes, to use for xfs_repair.  xfs_repair has its own inter-
              nal  block  cache  which  will scale out up to the lesser of the
              process's virtual address limit or about  75%  of  the  system's
              physical RAM.  This option overrides these limits.

              NOTE:  These memory limits are only approximate and may use more
              than the specified limit.

       -c subopt=value
              Change filesystem parameters. Refer to xfs_admin(8) for informa-
              tion on changing filesystem parameters.

       -o subopt[=value]
              Override what the program might conclude about the filesystem if
              left to its own devices.

              The suboptions supported are:

                 bhash=bhashsize
                        overrides the default buffer cache hash size. The  to-
                        tal  number  of  buffer cache entries are limited to 8
                        times this amount. The default size is set to  use  up
                        the  remainder  of  75%  of  the system's physical RAM
                        size.

                 ag_stride=ags_per_concat_unit
                        This creates additional processing threads to parallel
                        process  AGs that span multiple concat units. This can
                        significantly reduce  repair  times  on  concat  based
                        filesystems.

                 force_geometry
                        Check  the  filesystem  even  if  geometry information
                        could not be validated.  Geometry information can  not
                        be  validated if only a single allocation group exists
                        and thus we do not have a backup superblock available,
                        or  if there are two allocation groups and the two su-
                        perblocks do not agree  on  the  filesystem  geometry.
                        Only  use  this  option  if you validated the geometry
                        yourself and know what you are doing.  If In doubt run
                        in no modify mode first.

       -t  interval
              Modify  reporting  interval,  specified  in seconds. During long
              runs xfs_repair outputs its progress every 15 minutes. Reporting
              is only activated when ag_stride is enabled.

       -v     Verbose  output.   May  be  specified multiple times to increase
              verbosity.

       -d     Repair dangerously. Allow xfs_repair to repair an XFS filesystem
              mounted  read  only. This is typically done on a root filesystem
              from single user mode, immediately followed by a reboot.

       -e     If any metadata corruption was repaired, the status returned  is
              4  instead  of  the usual 0. This option cannot be used together
              with -n.

       -V     Prints the version number and exits.

   Checks Performed
       Inconsistencies corrected include the following:

       1.     Inode and inode blockmap (addressing) checks: bad  magic  number
              in  inode,  bad  magic numbers in inode blockmap blocks, extents
              out of order, incorrect number  of  records  in  inode  blockmap
              blocks,  blocks claimed that are not in a legal data area of the
              filesystem, blocks that are claimed by more than one inode.

       2.     Inode allocation map checks:  bad  magic  number  in  inode  map
              blocks,  inode state as indicated by map (free or in-use) incon-
              sistent with state indicated by the inode, inodes referenced  by
              the  filesystem  that do not appear in the inode allocation map,
              inode allocation map referencing blocks that do  not  appear  to
              contain inodes.

       3.     Size checks: number of blocks claimed by inode inconsistent with
              inode size, directory size not block  aligned,  inode  size  not
              consistent with inode format.

       4.     Directory  checks: bad magic numbers in directory blocks, incor-
              rect number of entries in a directory block, bad  freespace  in-
              formation  in a directory leaf block, entry pointing to an unal-
              located (free) or out of range inode, overlapping entries, miss-
              ing  or  incorrect  dot and dotdot entries, entries out of hash-
              value order, incorrect internal  directory  pointers,  directory
              type not consistent with inode format and size.

       5.     Pathname  checks: files or directories not referenced by a path-
              name starting from the filesystem root, illegal pathname  compo-
              nents.

       6.     Link count checks: link counts that do not agree with the number
              of directory references to the inode.

       7.     Freemap checks: blocks claimed free  by  the  freemap  but  also
              claimed  by  an inode, blocks unclaimed by any inode but not ap-
              pearing in the freemap.

       8.     Super Block checks: total free block and/or  free  i-node  count
              incorrect,  filesystem geometry inconsistent, secondary and pri-
              mary superblocks contradictory.

       Orphaned files and directories (allocated, in-use but unreferenced) are
       reconnected  by placing them in the lost+found directory.  The name as-
       signed is the inode number.

   Disk Errors
       xfs_repair aborts on most disk I/O errors. Therefore, if you are trying
       to  repair  a  filesystem that was damaged due to a disk drive failure,
       steps should be taken to ensure that all blocks in the  filesystem  are
       readable and writable before attempting to use xfs_repair to repair the
       filesystem. A possible method is using dd(8) to copy the  data  onto  a
       good disk.

   lost+found
       The directory lost+found does not have to already exist in the filesys-
       tem being repaired.  If the directory does not exist, it  is  automati-
       cally  created  if  required.  If it already exists, it will be checked
       for consistency and if valid  will  be  used  for  additional  orphaned
       files. Invalid lost+found directories are removed and recreated. Exist-
       ing files in a valid lost+found are not removed or renamed.

   Corrupted Superblocks
       XFS has both primary and secondary superblocks.  xfs_repair uses infor-
       mation in the primary superblock to automatically find and validate the
       primary superblock against the secondary superblocks before proceeding.
       Should  the  primary be too corrupted to be useful in locating the sec-
       ondary superblocks, the program scans the filesystem until it finds and
       validates  some  secondary  superblocks.  At that point, it generates a
       primary superblock.

   Quotas
       If quotas are in use, it is possible that xfs_repair will clear some or
       all  of  the filesystem quota information.  If so, the program issues a
       warning just before it terminates.  If all quota information  is  lost,
       quotas are disabled and the program issues a warning to that effect.

       Note that xfs_repair does not check the validity of quota limits. It is
       recommended that you check the quota limit information  manually  after
       xfs_repair.  Also, space usage information is automatically regenerated
       the next time the filesystem is mounted with quotas turned on,  so  the
       next quota mount of the filesystem may take some time.

DIAGNOSTICS
       xfs_repair  issues  informative messages as it proceeds indicating what
       it has found that is abnormal or any  corrective  action  that  it  has
       taken.   Most  of  the  messages  are completely understandable only to
       those who are knowledgeable about  the  structure  of  the  filesystem.
       Some  of  the  more  common messages are explained here.  Note that the
       language of the messages is slightly different if xfs_repair is run  in
       no-modify  mode  because  the program is not changing anything on disk.
       No-modify mode indicates what it would do to repair the  filesystem  if
       run without the no-modify flag.

       disconnected inode ino, moving to lost+found

              An inode numbered ino was not connected to the filesystem direc-
              tory tree and was reconnected to the lost+found  directory.  The
              inode  is  assigned  the  name  of its inode number (ino).  If a
              lost+found directory does not exist, it  is  automatically  cre-
              ated.

       disconnected dir inode ino, moving to lost+found

              As  above  only  the inode is a directory inode.  If a directory
              inode is attached to lost+found, all of its  children  (if  any)
              stay  attached  to the directory and therefore get automatically
              reconnected when the directory is reconnected.

       imap claims in-use inode ino is free, correcting imap

              The inode allocation map thinks that inode ino is  free  whereas
              examination  of the inode indicates that the inode may be in use
              (although it may be disconnected).  The program updates the  in-
              ode allocation map.

       imap claims free inode ino is in use, correcting imap

              The inode allocation map thinks that inode ino is in use whereas
              examination of the inode indicates that the inode is not in  use
              and therefore is free.  The program updates the inode allocation
              map.

       resetting inode ino nlinks from x to y

              The program detected a mismatch between the number of valid  di-
              rectory  entries  referencing inode ino and the number of refer-
              ences recorded in the inode and corrected the the number in  the
              inode.

       fork-type fork in ino ino claims used block bno

              Inode  ino  claims  a block bno that is used (claimed) by either
              another inode or the filesystem itself for metadata storage. The
              fork-type  is either data or attr indicating whether the problem
              lies in the portion of the inode that tracks regular data or the
              portion  of  the inode that stores XFS attributes.  If the inode
              is a real-time (rt) inode, the message says so.  Any inode  that
              claims blocks used by the filesystem is deleted.  If two or more
              inodes claim the same block, they are both deleted.

       fork-type fork in ino ino claims dup extent ...

              Inode ino claims a block in an extent known to be  claimed  more
              than once.  The offset in the inode, start and length of the ex-
              tent is given.  The message is slightly different if  the  inode
              is  a  real-time  (rt) inode and the extent is therefore a real-
              time (rt) extent.

       inode ino - bad extent ...

              An extent record in the blockmap of inode ino claims blocks that
              are  out of the legal range of the filesystem.  The message sup-
              plies the start, end, and file offset of the extent.   The  mes-
              sage is slightly different if the extent is a real-time (rt) ex-
              tent.

       bad fork-type fork in inode ino

              There was something structurally wrong or inconsistent with  the
              data structures that map offsets to filesystem blocks.

       cleared inode ino

              There  was something wrong with the inode that was uncorrectable
              so the program freed the inode.  This  usually  happens  because
              the  inode  claims blocks that are used by something else or the
              inode itself is badly corrupted. Typically, this message is pre-
              ceded by one or more messages indicating why the inode needed to
              be cleared.

       bad attribute fork in inode ino, clearing attr fork

              There was something wrong with the portion  of  the  inode  that
              stores  XFS attributes (the attribute fork) so the program reset
              the attribute fork.  As a result of this, all attributes on that
              inode are lost.

       correcting nextents for inode ino, was x - counted y

              The  program  found that the number of extents used to store the
              data in the inode is wrong and corrected the number.   The  mes-
              sage  refers  to nextents if the count is wrong on the number of
              extents used to store attribute information.

       entry name in dir dir_ino not consistent with .. value  (xxxx)  in  dir
       ino ino, junking entry name in directory inode dir_ino

              The entry name in directory inode dir_ino references a directory
              inode ino.  However, the .. entry  in  directory  ino  does  not
              point  back to directory dir_ino, so the program deletes the en-
              try name in directory inode dir_ino.  If the directory inode ino
              winds  up  becoming a disconnected inode as a result of this, it
              is moved to lost+found later.

       entry name in dir dir_ino references already  connected  dir  ino  ino,
       junking entry name in directory inode dir_ino

              The  entry name in directory inode dir_ino points to a directory
              inode ino that is known to be  a  child  of  another  directory.
              Therefore,  the  entry  is invalid and is deleted.  This message
              refers to an entry in a small directory.  If this were  a  large
              directory, the last phrase would read "will clear entry".

       entry references free inode ino in directory dir_ino, will clear entry

              An entry in directory inode dir_ino references an inode ino that
              is known to be free. The  entry  is  therefore  invalid  and  is
              deleted.   This message refers to a large directory.  If the di-
              rectory were small, the message would read "junking entry ...".

EXIT STATUS
       xfs_repair -n (no modify mode) will return a status of 1 if  filesystem
       corruption was detected and 0 if no filesystem corruption was detected.
       xfs_repair run without the -n option will always return a  status  code
       of  0  if it completes without problems, unless the flag -e is used. If
       it is used, then status 4 is reported when any issue with the  filesys-
       tem  was  found,  but could be fixed. If a runtime error is encountered
       during operation, it will return a status of 1. In this  case,  xfs_re-
       pair  should be restarted.  If xfs_repair is unable to proceed due to a
       dirty log, it will return a status of 2.  See below.

DIRTY LOGS
       Due to the design of the XFS log, a dirty log can only be  replayed  by
       the  kernel,  on  a machine having the same CPU architecture as the ma-
       chine which was writing to the log.  xfs_repair cannot replay  a  dirty
       log and will exit with a status code of 2 when it detects a dirty log.

       In  this situation, the log can be replayed by mounting and immediately
       unmounting the filesystem on the same class of  machine  that  crashed.
       Please make sure that the machine's hardware is reliable before replay-
       ing to avoid compounding the problems.

       If mounting fails, the log can be erased by running xfs_repair with the
       -L  option.   All metadata updates in progress at the time of the crash
       will be lost, which may  cause  significant  filesystem  damage.   This
       should only be used as a last resort.

BUGS
       The  filesystem  to  be  checked  and repaired must have been unmounted
       cleanly using normal system administration  procedures  (the  umount(8)
       command  or  system shutdown), not as a result of a crash or system re-
       set.  If the filesystem has not been unmounted cleanly,  mount  it  and
       unmount it cleanly before running xfs_repair.

       xfs_repair  does not do a thorough job on XFS extended attributes.  The
       structure of the attribute fork will be consistent, but only  the  con-
       tents of attribute forks that will fit into an inode are checked.  This
       limitation will be fixed in the future.

       The no-modify mode (-n option) is not completely accurate.  It does not
       catch  inconsistencies  in  the  freespace and inode maps, particularly
       lost blocks or subtly corrupted maps (trees).

       The no-modify mode can generate repeated warnings about the same  prob-
       lems because it cannot fix the problems as they are encountered.

       If a filesystem fails to be repaired, a metadump image can be generated
       with xfs_metadump(8) and be sent to an XFS maintainer  to  be  analysed
       and xfs_repair fixed and/or improved.

SEE ALSO
       dd(1), mkfs.xfs(8), umount(8), xfs_admin(8), xfs_metadump(8), xfs(5).

                                                                 xfs_repair(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | DIAGNOSTICS | EXIT STATUS | DIRTY LOGS | BUGS | SEE ALSO