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xfs_repair



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_spe­
       cial  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  external log resides.  Only for those
              filesystems which use an  external  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  realtime  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.


       -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) inconsistent 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, incorrect 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, directory type not consistent with  inode
              format and size.

       5.     Pathname  checks:  files  or directories not refer­
              enced by a pathname starting  from  the  filesystem
              root, illegal pathname components.

       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.

       that all blocks in the filesystem are readable and  write­
       able  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 filesystem being repaired.  If the directory does  not
       exist,  it  is  automatically  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 information 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 locat­
       ing the  secondary  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 termi­
       nates.  If all quota information is lost, quotas are  dis­
       abled 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 cor­
       rective action that it has taken.  Most  of  the  messages
       are completely understandable only to those who are knowl­
       edgeable 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
              directory inode is attached to lost+found,  all  of
              its  children  (if any) stay attached to the direc­
              tory 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 allo­
              cation 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 references 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 regu­
              lar 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 mes­
              sage 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 ...


              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  cor­
              rected  the number.  The message 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

       cedures (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 contents 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 problems 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)
  




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