1xfs_repair(8)               System Manager's Manual              xfs_repair(8)
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NAME

6       xfs_repair - repair an XFS filesystem
7

SYNOPSIS

9       xfs_repair  [  -dfLPv ] [ -n | -e ] [ -m maxmem ] [ -c subopt=value ] [
10       -o subopt[=value] ] [ -t interval ] [ -l logdev ] [ -r rtdev ] device
11       xfs_repair -V
12

DESCRIPTION

14       xfs_repair repairs corrupt or damaged  XFS  filesystems  (see  xfs(5)).
15       The  filesystem  is specified using the device argument which should be
16       the device name of the disk partition or volume containing the filesys‐
17       tem.  If  given  the name of a block device, xfs_repair will attempt to
18       find the raw device associated with the specified block device and will
19       use the raw device instead.
20
21       Regardless, the filesystem to be repaired must be unmounted, otherwise,
22       the resulting filesystem may be inconsistent or corrupt.
23

OPTIONS

25       -f     Specifies that the filesystem image to be processed is stored in
26              a regular file at device (see the mkfs.xfs -d file option). This
27              might happen if an image copy of a filesystem has been copied or
28              written into an ordinary file.  This option implies that any ex‐
29              ternal log or realtime section is also in an ordinary file.
30
31       -L     Force Log Zeroing.  Forces xfs_repair to zero the log even if it
32              is  dirty  (contains  metadata changes).  When using this option
33              the filesystem will likely appear to be corrupt, and  can  cause
34              the  loss of user files and/or data.  See the DIRTY LOGS section
35              for more information.
36
37       -l logdev
38              Specifies the device special file where the filesystem's  exter‐
39              nal  log resides. Only for those filesystems which use an exter‐
40              nal log.  See the mkfs.xfs -l option, and refer to xfs(5) for  a
41              detailed description of the XFS log.
42
43       -r rtdev
44              Specifies  the  device special file where the filesystem's real‐
45              time section resides. Only for those filesystems which use a re‐
46              altime section.  See the mkfs.xfs -r option, and refer to xfs(5)
47              for a detailed description of the XFS realtime section.
48
49       -n     No modify mode. Specifies that xfs_repair should not modify  the
50              filesystem but should only scan the filesystem and indicate what
51              repairs would have been made. This option  cannot  be  used  to‐
52              gether with -e.
53
54       -P     Disable  prefetching of inode and directory blocks. Use this op‐
55              tion if you find xfs_repair gets stuck and stops proceeding. In‐
56              terrupting a stuck xfs_repair is safe.
57
58       -m maxmem
59              Specifies   the   approximate   maximum  amount  of  memory,  in
60              megabytes, to use for xfs_repair.  xfs_repair has its own inter‐
61              nal  block  cache  which  will scale out up to the lesser of the
62              process's virtual address limit or about  75%  of  the  system's
63              physical RAM.  This option overrides these limits.
64
65              NOTE:  These memory limits are only approximate and may use more
66              than the specified limit.
67
68       -c subopt=value
69              Change filesystem parameters. Refer to xfs_admin(8) for informa‐
70              tion on changing filesystem parameters.
71
72       -o subopt[=value]
73              Override what the program might conclude about the filesystem if
74              left to its own devices.
75
76              The suboptions supported are:
77
78                 bhash=bhashsize
79                        overrides the default buffer cache hash size. The  to‐
80                        tal  number  of  buffer cache entries are limited to 8
81                        times this amount. The default size is set to  use  up
82                        the  remainder  of  75%  of  the system's physical RAM
83                        size.
84
85                 ag_stride=ags_per_concat_unit
86                        This creates additional processing threads to parallel
87                        process  AGs that span multiple concat units. This can
88                        significantly reduce  repair  times  on  concat  based
89                        filesystems.
90
91                 force_geometry
92                        Check  the  filesystem  even  if  geometry information
93                        could not be validated.  Geometry information can  not
94                        be  validated if only a single allocation group exists
95                        and thus we do not have a backup superblock available,
96                        or  if there are two allocation groups and the two su‐
97                        perblocks do not agree  on  the  filesystem  geometry.
98                        Only  use  this  option  if you validated the geometry
99                        yourself and know what you are doing.  If In doubt run
100                        in no modify mode first.
101
102                 noquota
103                        Don't validate quota counters at all.  Quotacheck will
104                        be run during the next mount to recalculate  all  val‐
105                        ues.
106
107       -t  interval
108              Modify  reporting  interval,  specified  in seconds. During long
109              runs xfs_repair outputs its progress every 15 minutes. Reporting
110              is only activated when ag_stride is enabled.
111
112       -v     Verbose  output.   May  be  specified multiple times to increase
113              verbosity.
114
115       -d     Repair dangerously. Allow xfs_repair to repair an XFS filesystem
116              mounted  read  only. This is typically done on a root filesystem
117              from single user mode, immediately followed by a reboot.
118
119       -e     If any metadata corruption was repaired, the status returned  is
120              4  instead  of  the usual 0. This option cannot be used together
121              with -n.
122
123       -V     Prints the version number and exits.
124
125   Checks Performed
126       Inconsistencies corrected include the following:
127
128       1.     Inode and inode blockmap (addressing) checks: bad  magic  number
129              in  inode,  bad  magic numbers in inode blockmap blocks, extents
130              out of order, incorrect number  of  records  in  inode  blockmap
131              blocks,  blocks claimed that are not in a legal data area of the
132              filesystem, blocks that are claimed by more than one inode.
133
134       2.     Inode allocation map checks:  bad  magic  number  in  inode  map
135              blocks,  inode state as indicated by map (free or in-use) incon‐
136              sistent with state indicated by the inode, inodes referenced  by
137              the  filesystem  that do not appear in the inode allocation map,
138              inode allocation map referencing blocks that do  not  appear  to
139              contain inodes.
140
141       3.     Size checks: number of blocks claimed by inode inconsistent with
142              inode size, directory size not block  aligned,  inode  size  not
143              consistent with inode format.
144
145       4.     Directory  checks: bad magic numbers in directory blocks, incor‐
146              rect number of entries in a directory block, bad  freespace  in‐
147              formation  in a directory leaf block, entry pointing to an unal‐
148              located (free) or out of range inode, overlapping entries, miss‐
149              ing  or  incorrect  dot and dotdot entries, entries out of hash‐
150              value order, incorrect internal  directory  pointers,  directory
151              type not consistent with inode format and size.
152
153       5.     Pathname  checks: files or directories not referenced by a path‐
154              name starting from the filesystem root, illegal pathname  compo‐
155              nents.
156
157       6.     Link count checks: link counts that do not agree with the number
158              of directory references to the inode.
159
160       7.     Freemap checks: blocks claimed free  by  the  freemap  but  also
161              claimed  by  an inode, blocks unclaimed by any inode but not ap‐
162              pearing in the freemap.
163
164       8.     Super Block checks: total free block and/or  free  i-node  count
165              incorrect,  filesystem geometry inconsistent, secondary and pri‐
166              mary superblocks contradictory.
167
168       Orphaned files and directories (allocated, in-use but unreferenced) are
169       reconnected  by placing them in the lost+found directory.  The name as‐
170       signed is the inode number.
171
172   Disk Errors
173       xfs_repair aborts on most disk I/O errors. Therefore, if you are trying
174       to  repair  a  filesystem that was damaged due to a disk drive failure,
175       steps should be taken to ensure that all blocks in the  filesystem  are
176       readable and writable before attempting to use xfs_repair to repair the
177       filesystem. A possible method is using dd(8) to copy the  data  onto  a
178       good disk.
179
180   lost+found
181       The directory lost+found does not have to already exist in the filesys‐
182       tem being repaired.  If the directory does not exist, it  is  automati‐
183       cally  created  if  required.  If it already exists, it will be checked
184       for consistency and if valid  will  be  used  for  additional  orphaned
185       files. Invalid lost+found directories are removed and recreated. Exist‐
186       ing files in a valid lost+found are not removed or renamed.
187
188   Corrupted Superblocks
189       XFS has both primary and secondary superblocks.  xfs_repair uses infor‐
190       mation in the primary superblock to automatically find and validate the
191       primary superblock against the secondary superblocks before proceeding.
192       Should  the  primary be too corrupted to be useful in locating the sec‐
193       ondary superblocks, the program scans the filesystem until it finds and
194       validates  some  secondary  superblocks.  At that point, it generates a
195       primary superblock.
196
197   Quotas
198       If quotas are in use, it is possible that xfs_repair will clear some or
199       all  of  the filesystem quota information.  If so, the program issues a
200       warning just before it terminates.  If all quota information  is  lost,
201       quotas are disabled and the program issues a warning to that effect.
202
203       Note that xfs_repair does not check the validity of quota limits. It is
204       recommended that you check the quota limit information  manually  after
205       xfs_repair.  Also, space usage information is automatically regenerated
206       the next time the filesystem is mounted with quotas turned on,  so  the
207       next quota mount of the filesystem may take some time.
208

DIAGNOSTICS

210       xfs_repair  issues  informative messages as it proceeds indicating what
211       it has found that is abnormal or any  corrective  action  that  it  has
212       taken.   Most  of  the  messages  are completely understandable only to
213       those who are knowledgeable about  the  structure  of  the  filesystem.
214       Some  of  the  more  common messages are explained here.  Note that the
215       language of the messages is slightly different if xfs_repair is run  in
216       no-modify  mode  because  the program is not changing anything on disk.
217       No-modify mode indicates what it would do to repair the  filesystem  if
218       run without the no-modify flag.
219
220       disconnected inode ino, moving to lost+found
221
222              An inode numbered ino was not connected to the filesystem direc‐
223              tory tree and was reconnected to the lost+found  directory.  The
224              inode  is  assigned  the  name  of its inode number (ino).  If a
225              lost+found directory does not exist, it  is  automatically  cre‐
226              ated.
227
228       disconnected dir inode ino, moving to lost+found
229
230              As  above  only  the inode is a directory inode.  If a directory
231              inode is attached to lost+found, all of its  children  (if  any)
232              stay  attached  to the directory and therefore get automatically
233              reconnected when the directory is reconnected.
234
235       imap claims in-use inode ino is free, correcting imap
236
237              The inode allocation map thinks that inode ino is  free  whereas
238              examination  of the inode indicates that the inode may be in use
239              (although it may be disconnected).  The program updates the  in‐
240              ode allocation map.
241
242       imap claims free inode ino is in use, correcting imap
243
244              The inode allocation map thinks that inode ino is in use whereas
245              examination of the inode indicates that the inode is not in  use
246              and therefore is free.  The program updates the inode allocation
247              map.
248
249       resetting inode ino nlinks from x to y
250
251              The program detected a mismatch between the number of valid  di‐
252              rectory  entries  referencing inode ino and the number of refer‐
253              ences recorded in the inode and corrected the the number in  the
254              inode.
255
256       fork-type fork in ino ino claims used block bno
257
258              Inode  ino  claims  a block bno that is used (claimed) by either
259              another inode or the filesystem itself for metadata storage. The
260              fork-type  is either data or attr indicating whether the problem
261              lies in the portion of the inode that tracks regular data or the
262              portion  of  the inode that stores XFS attributes.  If the inode
263              is a real-time (rt) inode, the message says so.  Any inode  that
264              claims blocks used by the filesystem is deleted.  If two or more
265              inodes claim the same block, they are both deleted.
266
267       fork-type fork in ino ino claims dup extent ...
268
269              Inode ino claims a block in an extent known to be  claimed  more
270              than once.  The offset in the inode, start and length of the ex‐
271              tent is given.  The message is slightly different if  the  inode
272              is  a  real-time  (rt) inode and the extent is therefore a real-
273              time (rt) extent.
274
275       inode ino - bad extent ...
276
277              An extent record in the blockmap of inode ino claims blocks that
278              are  out of the legal range of the filesystem.  The message sup‐
279              plies the start, end, and file offset of the extent.   The  mes‐
280              sage is slightly different if the extent is a real-time (rt) ex‐
281              tent.
282
283       bad fork-type fork in inode ino
284
285              There was something structurally wrong or inconsistent with  the
286              data structures that map offsets to filesystem blocks.
287
288       cleared inode ino
289
290              There  was something wrong with the inode that was uncorrectable
291              so the program freed the inode.  This  usually  happens  because
292              the  inode  claims blocks that are used by something else or the
293              inode itself is badly corrupted. Typically, this message is pre‐
294              ceded by one or more messages indicating why the inode needed to
295              be cleared.
296
297       bad attribute fork in inode ino, clearing attr fork
298
299              There was something wrong with the portion  of  the  inode  that
300              stores  XFS attributes (the attribute fork) so the program reset
301              the attribute fork.  As a result of this, all attributes on that
302              inode are lost.
303
304       correcting nextents for inode ino, was x - counted y
305
306              The  program  found that the number of extents used to store the
307              data in the inode is wrong and corrected the number.   The  mes‐
308              sage  refers  to nextents if the count is wrong on the number of
309              extents used to store attribute information.
310
311       entry name in dir dir_ino not consistent with .. value  (xxxx)  in  dir
312       ino ino, junking entry name in directory inode dir_ino
313
314              The entry name in directory inode dir_ino references a directory
315              inode ino.  However, the .. entry  in  directory  ino  does  not
316              point  back to directory dir_ino, so the program deletes the en‐
317              try name in directory inode dir_ino.  If the directory inode ino
318              winds  up  becoming a disconnected inode as a result of this, it
319              is moved to lost+found later.
320
321       entry name in dir dir_ino references already  connected  dir  ino  ino,
322       junking entry name in directory inode dir_ino
323
324              The  entry name in directory inode dir_ino points to a directory
325              inode ino that is known to be  a  child  of  another  directory.
326              Therefore,  the  entry  is invalid and is deleted.  This message
327              refers to an entry in a small directory.  If this were  a  large
328              directory, the last phrase would read "will clear entry".
329
330       entry references free inode ino in directory dir_ino, will clear entry
331
332              An entry in directory inode dir_ino references an inode ino that
333              is known to be free. The  entry  is  therefore  invalid  and  is
334              deleted.   This message refers to a large directory.  If the di‐
335              rectory were small, the message would read "junking entry ...".
336

EXIT STATUS

338       xfs_repair -n (no modify mode) will return a status of 1 if  filesystem
339       corruption was detected and 0 if no filesystem corruption was detected.
340       xfs_repair run without the -n option will always return a  status  code
341       of  0  if it completes without problems, unless the flag -e is used. If
342       it is used, then status 4 is reported when any issue with the  filesys‐
343       tem  was  found,  but could be fixed. If a runtime error is encountered
344       during operation, it will return a status of 1. In this  case,  xfs_re‐
345       pair  should be restarted.  If xfs_repair is unable to proceed due to a
346       dirty log, it will return a status of 2.  See below.
347

DIRTY LOGS

349       Due to the design of the XFS log, a dirty log can only be  replayed  by
350       the  kernel,  on  a machine having the same CPU architecture as the ma‐
351       chine which was writing to the log.  xfs_repair cannot replay  a  dirty
352       log and will exit with a status code of 2 when it detects a dirty log.
353
354       In  this situation, the log can be replayed by mounting and immediately
355       unmounting the filesystem on the same class of  machine  that  crashed.
356       Please make sure that the machine's hardware is reliable before replay‐
357       ing to avoid compounding the problems.
358
359       If mounting fails, the log can be erased by running xfs_repair with the
360       -L  option.   All metadata updates in progress at the time of the crash
361       will be lost, which may  cause  significant  filesystem  damage.   This
362       should only be used as a last resort.
363

BUGS

365       The  filesystem  to  be  checked  and repaired must have been unmounted
366       cleanly using normal system administration  procedures  (the  umount(8)
367       command  or  system shutdown), not as a result of a crash or system re‐
368       set.  If the filesystem has not been unmounted cleanly,  mount  it  and
369       unmount it cleanly before running xfs_repair.
370
371       xfs_repair  does not do a thorough job on XFS extended attributes.  The
372       structure of the attribute fork will be consistent, but only  the  con‐
373       tents of attribute forks that will fit into an inode are checked.  This
374       limitation will be fixed in the future.
375
376       The no-modify mode (-n option) is not completely accurate.  It does not
377       catch  inconsistencies  in  the  freespace and inode maps, particularly
378       lost blocks or subtly corrupted maps (trees).
379
380       The no-modify mode can generate repeated warnings about the same  prob‐
381       lems because it cannot fix the problems as they are encountered.
382
383       If a filesystem fails to be repaired, a metadump image can be generated
384       with xfs_metadump(8) and be sent to an XFS maintainer  to  be  analysed
385       and xfs_repair fixed and/or improved.
386

SEE ALSO

388       dd(1), mkfs.xfs(8), umount(8), xfs_admin(8), xfs_metadump(8), xfs(5).
389
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392                                                                 xfs_repair(8)
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