FSCK_FFS(8)             OpenBSD System Manager's Manual            FSCK_FFS(8)

NAME
     fsck_ffs - Fast File System consistency check and interactive repair

SYNOPSIS
     fsck_ffs [-fnpy] [-b block#] [-c level] [-m mode] filesystem ...

DESCRIPTION
     fsck_ffs performs interactive file system consistency checks and repairs
     for each file system specified.  It is normally invoked from fsck(8).

     The kernel takes care that only a restricted class of innocuous file sys-
     tem inconsistencies can happen unless hardware or software failures in-
     tervene.  These are limited to the following:

           Unreferenced inodes
           Link counts in inodes too large
           Missing blocks in the free map
           Blocks in the free map also in files
           Counts in the super-block wrong

     These are the only inconsistencies that fsck_ffs with the -p option will
     correct; if it encounters other inconsistencies, it exits with an abnor-
     mal return status and an automatic reboot will then fail.  For each cor-
     rected inconsistency, one or more lines will be printed identifying the
     file system on which the correction will take place along with the nature
     of the correction.  After successfully correcting a file system, fsck_ffs
     will print the number of files on that file system, the number of used
     and free blocks, and the percentage of fragmentation.

     If sent a QUIT signal, fsck_ffs will finish the file system checks, then
     exit with an abnormal return status that causes an automatic reboot to
     fail.  This is useful when you want to finish the file system checks dur-
     ing an automatic reboot, but do not want the machine to come up multiuser
     after the checks complete.

     If sent an INFO signal, fsck_ffs will print a line to standard error in-
     dicating the name of the device currently being checked, the current
     phase number, and phase-specific progress information.

     Without the -p option, fsck_ffs audits and interactively repairs incon-
     sistent conditions for file systems.  If the file system is inconsistent,
     the operator is prompted for concurrence before each correction is at-
     tempted.  It should be noted that some of the corrective actions which
     are not correctable under the -p option will result in some loss of data.
     The amount and severity of data lost may be determined from the diagnos-
     tic output.  The default action for each consistency correction is to
     wait for the operator to respond ``yes'' or ``no''.  If the operator does
     not have write permission on the file system, fsck_ffs will default to a
     -n action.

     fsck has more consistency checks than its predecessors check, dcheck,
     fcheck, and icheck combined.

     The following flags are interpreted by fsck_ffs:

     -b block#
             Use the block# specified as the super block for the file system.
             Block 32 is usually an alternate super block.

     -c level
             Convert the file system to the specified level.  Note that the
             level of a file system can only be raised.  There are currently
             four levels defined:

             0       The file system is in the old (static table) format.

             1       The file system is in the new (dynamic table) format.

             2       The file system supports 32-bit UIDs and GIDs, short sym-
                     bolic links are stored in the inode, and directories have
                     an added field showing the file type.

             3       If maxcontig is greater than one, build the free segment
                     maps to aid in finding contiguous sets of blocks.  If
                     maxcontig is equal to one, delete any existing segment
                     maps.

     -f      Force checking of file systems.  Normally, if a file system is
             cleanly unmounted, the kernel will set a ``clean flag'' in the
             file system superblock and fsck_ffs will not check the file sys-
             tem.  This option forces fsck_ffs to check the file system, re-
             gardless of the state of the clean flag.

     -m mode
             Use the mode specified in octal as the permission bits to use
             when creating the lost+found directory rather than the default
             1700.  In particular, systems that wish to have lost files acces-
             sible by all users on the system should use a less restrictive
             set of permissions such as 755.

     -n      Assume a ``no'' response to all questions asked by fsck_ffs ex-
             cept for ``CONTINUE?'', which is assumed to be affirmative.  File
             systems will not be opened for writing.  This is the default for
             file systems to be checked that are concurrently mounted
             writable.

     -p      Enter preen mode: fsck_ffs will check the file systems on the
             special (raw) devices listed on the command line and will make
             minor repairs without human intervention.  Any major problems
             will cause fsck_ffs to exit with a non-zero exit code, so as to
             alert any invoking program or script that human intervention is
             required.

     -y      Assume a ``yes'' response to all questions asked by fsck_ffs;
             this should be used with great caution as this is a free license
             to continue after essentially unlimited trouble has been encoun-
             tered.

     In interactive mode, fsck_ffs will list the conversion to be made and ask
     whether the conversion should be done.  If a negative answer is given, no
     further operations are done on the file system.  In preen mode, the con-
     version is listed and done if possible without user interaction.  Conver-
     sion in preen mode is best used when all the file systems are being con-
     verted at once.  The format of a file system can be determined from the
     first line of output from dumpfs(8).

     Inconsistencies checked are as follows:

     1.   Blocks claimed more than once by inodes or the free map.
     2.   Blocks claimed by an inode outside the range of the file system.
     3.   Incorrect link counts.
     4.   Size checks:
                Directory size not a multiple of DIRBLKSIZ.
                Partially truncated file.
     5.   Bad inode format.
     6.   Blocks not accounted for anywhere.
     7.   Directory checks:
                File pointing to unallocated inode.
                Inode number out of range.
                Dot or dot-dot not the first two entries of a directory or
                having the wrong inode number.
     8.   Super Block checks:
                More blocks for inodes than there are in the file system.
                Bad free block map format.
                Total free block and/or free inode count incorrect.

     Orphaned files and directories (allocated but unreferenced) are, with the
     operator's concurrence, reconnected by placing them in the lost+found di-
     rectory.  The name assigned is the inode number.  If the lost+found di-
     rectory does not exist, it is created.  If there is insufficient space
     its size is increased.

     Because of inconsistencies between the block device and the buffer cache,
     the raw device should always be used.

DIAGNOSTICS
     The diagnostics produced by fsck_ffs are fully enumerated and explained
     in Appendix A of Fsck_ffs - The UNIX File System Check Program.

SEE ALSO
     fs(5), fstab(5), fsck(8), fsdb(8), growfs(8), mount_ffs(8), newfs(8),
     rc(8)

OpenBSD 4.7                      March 3, 2010                               3
