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xfs_repair(1M)
NAME
xfs_repair - repair an XFS filesystem
SYNOPSIS
xfs_repair [ -n ] [ -L ] [ -o subopt[=value] ] xfs_special
xfs_repair -f [ -n ] [ -L ] [ -o subopt[=value] ] ... file
xfs_repair64 [ -n ] [ -L ] [ -o subopt[=value] ] xfs_special
xfs_repair64 -f [ -n ] [ -L ] [ -o subopt[=value] ] ... file
DESCRIPTION
xfs_repair repairs corrupt or damaged XFS filesystems (see xfs(4)).
xfs_repair does not work on EFS filesystems (see fsck(1M)). 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.
xfs_repair is an n32 binary and will run on all Irix platforms. However,
when repairing a multi-terabyte filesystem, the memory requirements
exceed what is available to n32 binaries. For those filesystems,
xfs_repair64, 64-bit binary, should be used.
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.
-L Force Log Zeroing. Forces xfs_repair to zero the log even if there
is metadata in it. When using this option the filesystem will
likely appear to be corrupt, and can cause the loss of user files
and/or data.
-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.
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 referenced 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.
8. Super Block checks: total free block and/or free i-node count
incorrect, filesystem geometry inconsistent, secondary and primary
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 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 writeable before attempting to use xfs_repair to repair the
filesystem. Possible methods include using dd(1M) to copy the data onto
a good disk or fx(1M) to remap bad blocks if the block numbers are known.
fx(1M), if used, should be used with extreme caution.
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 locating
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 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
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 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 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 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 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(1M), fx(1M), mkfs_xfs(1M), xfs_check(1M), xfs(4), xlv(7M).
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