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



NAME
       xfs_repair - repair an XFS filesystem

SYNOPSIS
       xfs_repair [ -nLvVd ] [ -o subopt[=value] ]
            [-l logdev] [-r rtdev] xfs_special

       xfs_repair -f [ -nLvVd ] [ -o subopt[=value] ]
            [-l logfile] [-r rtfile] file

DESCRIPTION
       xfs_repair  repairs  corrupt  or  damaged XFS filesystems (see xfs(5)).
       The filesystem is specified using the xfs_special argument which should
       be  the  device  name  of  the  disk partition or volume containing the
       filesystem.  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.

       The options to xfs_repair 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 copied or written into an ordinary file.
              This option implies that any external 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.

       -l     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     Specifies  the  device special file where the filesystem's real-
              time section resides.  Only for those filesystems  which  use  a
              realtime  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.

       -o     Override what the program might conclude about the filesystem if
              left to its own devices.

              The assume_xfs suboption specifies that the filesystem is an XFS
              filesystem.   Normally,  if  xfs_repair  cannot  find   an   XFS
              superblock,  it  checks  to  see  if  the  filesystem  is an EFS
              filesystem before it tries to regenerate the XFS superblock.  If
              the  assume_xfs option is in effect, xfs_repair will assume that
              the filesystem is an XFS  filesystem  and  will  ignore  an  EFS
              superblock if one is found.

       -v     Verbose output.

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

   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
              information in a directory leaf  block,  entry  pointing  to  an
              unallocated  (free)  or out of range inode, overlapping entries,
              missing or incorrect dot and  dotdot  entries,  entries  out  of
              hashvalue  order,  incorrect internal directory pointers, direc-
              tory 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
              appearing 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
       assigned is the inode number.

   Disk Errors
       xfs_repair  aborts on most disk I/O errors.  Therefore, if you are try-
       ing to repair a filesystem that was damaged due to a disk  drive  fail-
       ure,  steps should be taken to ensure that all blocks in the filesystem
       are readable and writeable  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  the  lost+found  directory  already  exists,  the
       lost+found  directory  is  deleted  and recreated every time xfs_repair
       runs.  This ensures that there are no  name  conflicts  in  lost+found.
       However,  if  you  rename  a  file in lost+found and leave it there, if
       xfs_repair is run again, that file is renamed back to its inode number.

   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 xxxx, moving to lost+found

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

       disconnected dir inode xxxx, 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 xxxx is free, correcting imap

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

       imap claims free inode xxxx is in use, correcting imap

              The  inode  allocation  map  thinks  that  inode  xxxx 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 xxxx nlinks from x to y

              The program detected a mismatch  between  the  number  of  valid
              directory  entries referencing inode xxxx and the number of ref-
              erences recorded in the inode and corrected the  the  number  in
              the inode.

       fork-type fork in ino xxxx claims used block yyyy

              Inode  xxxx claims a block yyyy 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 xxxx claims dup extent ...

              Inode xxxx claims a block in an extent known to be claimed  more
              than  once.   The  offset  in the inode, start and length of the
              extent 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 xxxx - bad extent ...

              An extent record in the blockmap of  inode  xxxx  claims  blocks
              that  are out of the legal range of the filesystem.  The message
              supplies the start, end, and file offset  of  the  extent.   The
              message  is slightly different if the extent is a real-time (rt)
              exent.

       bad fork-type fork in inode xxxx

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

       cleared inode xxxx

              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
              preceded by one or more messages indicating why the inode needed
              to be cleared.

       bad attribute fork in inode xxxx, 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 xxxx, 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 xxxx not consistent with ..  value  (yyyy)  in  dir
       ino xxxx, junking entry "name" in directory inode xxxx

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

       entry "name" in dir xxxx references already  connected  dir  ino  yyyy,
       junking entry "name" in directory inode xxxx

              The  entry  "name" in directory inode xxxx points to a directory
              inode yyyy 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 xxxx in directory yyyy, will clear entry

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

EXIT STATUS
       xfs_repair  -n (no modify node) 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.

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
       reset.   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.

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



                                                                 xfs_repair(8)