fsck_ufs(1M) System Administration Commands fsck_ufs(1M)NAMEfsck_ufs - 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 inconsistent condi‐
tions 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 device, for
example, /dev/rdsk/c1t0d0s7, on which the file system 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 per‐
mission on the file system, 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 diag‐
nostic output.
The fsck utility automatically corrects innocuous inconsistencies 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 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 successfully 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:
· Blocks claimed by more than one inode or the free list.
· Blocks claimed by an inode or the free list outside the range of
the file system.
· Incorrect link counts.
· Incorrect directory sizes.
· Bad inode format.
· Blocks not accounted for anywhere.
· Directory checks, file pointing to unallocated inode, inode number
out of range, and absence of `.' and `..' as the first two entries
in each directory.
· Super Block checks: more blocks for inodes than there are in the
file system.
· Bad free block list 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 directory. The name assigned is the inode number. If the
lost+found directory does not exist, it is created. If there is insuf‐
ficient space in the lost+found directory, its size is increased.
An attempt to mount a ufs file system with the -o nolargefiles 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 mount
attempt indicates the presence of at least one large file. See
mount_ufs(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 dis‐
plays a message such as:
ufs fsck: sanity check:
/dev/rdsk/c0t3d0s1 okay
-n|N 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 implementa‐
tions.
-y|Y 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 intervening spa‐
ces).
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 loca‐
tion of other super blocks by running
newfs(1M) with the -Nv options specified.
f
Force checking of file systems regardless
of the state of their super block clean
flag.
p
Check and fix the file system non-interac‐
tively ("preen"). Exit immediately if there
is a problem requiring intervention. 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 system
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOclri(1M), fsck(1M), fsdb_ufs(1M), fsirand(1M), fstyp(1M), mkfs(1M),
mkfs_ufs(1M), mount_ufs(1M), mountall(1M), newfs(1M), reboot(1M),
vfstab(4), attributes(5), largefile(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 file sys‐
tem 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?
SunOS 5.10 2 Aug 2005 fsck_ufs(1M)
