System Administration Commands fsckufs(1M)
NAME
fsckufs - file system consistency check and interactive
repair
SYNOPSIS
fsck -F ufs [generic-options] [special]...
fsck -F ufs [generic-options] [-o specific-options]
[special]...
DESCRIPTION
The fsck utility audits and interactively repairs incon-
sistent conditions on file systems. A file system to be
checked may be specified by giving the name of the block or
character special device or by giving the name of its mount
point if a matching entry exists in /etc/vfstab.
The special parameter represents the character special dev-
ice, for example, /dev/rdsk/c1t0d0s7, on which the file sys-
tem resides. The character special device, not the block
special device should be used. The fsck utility will not
work if the block device is mounted, unless the file system
is error-locked.
If no special device is specified, all ufs file systems
specified in the vfstab with a fsckdev entry will be
checked. If the -p (``preen'') option is specified, ufs file
systems with an fsckpass number greater than 1 are checked
in parallel. See fsck(1M).
In the case of correcting serious inconsistencies, by
default, fsck asks for confirmation before making a repair
and waits for the operator to respond either yes or no. If
the operator does not have write permission on the file sys-
tem, fsck will default to a -n (no corrections) action. See
fsck(1M).
Repairing some file system inconsistencies can result in
loss of data. The amount and severity of data loss can be
determined from the diagnostic output.
The fsck utility automatically corrects innocuous incon-
sistencies such as unreferenced inodes, too-large link
counts in inodes, missing blocks in the free list, blocks
appearing in the free list and also in files, or incorrect
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System Administration Commands fsckufs(1M)
counts in the super block. It displays a message for each
inconsistency corrected that identifies the nature of the
correction on the file system which took place. After suc-
cessfully correcting a file system, fsck prints the number
of files on that file system, the number of used and free
blocks, and the percentage of fragmentation.
Inconsistencies checked include:
o Blocks claimed by more than one inode or the free
list.
o Blocks claimed by an inode or the free list outside
the range of the file system.
o Incorrect link counts.
o Incorrect directory sizes.
o Bad inode format.
o Blocks not accounted for anywhere.
o Directory checks, file pointing to unallocated
inode, inode number out of range, and absence of
`.' and `..' as the first two entries in each
directory.
o Super Block checks: more blocks for inodes than
there are in the file system.
o Bad free block list format.
o 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 directory. The name assigned is the
inode number. If the lost]found directory does not exist, it
is created. If there is insufficient space in the lost]found
directory, its size is increased.
An attempt to mount a ufs file system with the -o nolarge-
files option will fail if the file system has ever contained
a large file (a file whose size is greater than or equal to
2 Gbyte). Invoking fsck resets the file system state if no
large files are present in the file system. A successful
mount of the file system after invoking fsck indicates the
absence of large files in the file system. An unsuccessful
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System Administration Commands fsckufs(1M)
mount attempt indicates the presence of at least one large
file. See mountufs(1M).
OPTIONS
The generic-options consist of the following options:
-m Check but do not repair. This option checks that
the file system is suitable for mounting,
returning the appropriate exit status. If the
file system is ready for mounting, fsck displays
a message such as:
ufs fsck: sanity check: /dev/rdsk/c0t3d0s1
okay
-nN Assume a no response to all questions asked by
fsck; do not open the file system for writing.
-V Echo the expanded command line, but do not exe-
cute the command. This option may be used to
verify and to validate the command line.
-v Enables verbose output. Might not be supported
by all filesystem-specific fsck implementations.
-yY Assume a yes response to all questions asked by
fsck.
See generic fsck(1M) for the details for specifying special.
-o specific-options Specify ufs file system specific
options. These options can be any
combination of the following
separated by commas (with no inter-
vening spaces).
b=n Use block n as the super block
for the file system. Block 32
is always one of the alternate
super blocks. Determine the
location of other super blocks
by running newfs(1M) with the
-Nv options specified.
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System Administration Commands fsckufs(1M)
f Force checking of file systems
regardless of the state of
their super block clean flag.
p Check and fix the file system
non-interactively ("preen").
Exit immediately if there is a
problem requiring interven-
tion. This option is required
to enable parallel file system
checking.
w Check writable file systems
only.
FILES
/etc/vfstab list of default parameters for each file sys-
tem
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
SEE ALSO
clri(1M), fsck(1M), fsdbufs(1M), fsirand(1M), fstyp(1M),
mkfs(1M), mkfsufs(1M), mountufs(1M), mountall(1M),
newfs(1M), reboot(1M), vfstab(4), attributes(5), large-
file(5), ufs(7FS)
WARNINGS
The operating system buffers file system data. Running fsck
on a mounted file system can cause the operating system's
buffers to become out of date with respect to the disk. For
this reason, the file system should be unmounted when fsck
is used. If this is not possible, care should be taken that
the system is quiescent and that it is rebooted immediately
after fsck is run. Quite often, however, this will not be
sufficient. A panic will probably occur if running fsck on a
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System Administration Commands fsckufs(1M)
file system modifies the file system.
NOTES
It is usually faster to check the character special device
than the block special device.
Running fsck on file systems larger than 2 Gb fails if the
user chooses to use the block interface to the device:
fsck /dev/dsk/c?t?d?s?
rather than the raw (character special) device:
fsck /dev/rdsk/c?t?d?s?
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