NAME
fsck_lfs —
Log-structured File System
consistency check and interactive repair
SYNOPSIS
fsck_lfs |
[-dfpqU]
[-b block]
[-m mode]
[-y | -n]
filesystem ... |
DESCRIPTION
fsck_lfs performs interactive filesystem consistency checks
and repair for each of the filesystems specified on the command line. It is
normally invoked from
fsck(8).
The design of LFS takes care that no filesystem inconsistencies can happen
unless hardware or software failures intervene.
fsck_lfs
will report and optionally correct any such inconsistencies.
For each corrected inconsistency one or more lines will be printed identifying
the filesystem on which the correction will take place, and the nature of the
correction. After successfully correcting a filesystem,
fsck_lfs will print the number of files on that filesystem,
the number of used and free blocks, and the percentage of fragmentation.
If sent a
QUIT
signal,
fsck_lfs will
finish the filesystem checks, then exit with an abnormal return status.
Without the
-p option,
fsck_lfs audits and
interactively repairs inconsistent conditions for filesystems. If the
filesystem is inconsistent, the operator is prompted for concurrence before
each correction is attempted. It should be noted that some of the corrective
actions will result in some loss of data. The amount and severity of data lost
may be determined from the diagnostic 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 filesystem
fsck_lfs
will default to a
-n action.
The following flags are interpreted by
fsck_lfs:
-
-
- -b
block
- Use block as the super block for the
filesystem.
-
-
- -d
- Print debugging output.
-
-
- -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_lfs will not check
the file system. This option forces fsck_lfs to check
the file system, regardless of the state of the clean flag.
-
-
- -m
mode
- Use 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 do not
wish to have lost files accessible by all users on the system should use a
more restrictive set of permissions such as 700.
-
-
- -n
- Assume a no response to all questions asked by
fsck_lfs except for
‘
CONTINUE?
’, which is assumed to be
affirmative; do not open the filesystem for writing.
-
-
- -p
- Specify “preen” mode. Currently, in this mode
fsck_lfs does nothing.
-
-
- -q
- Quiet mode, do not output any messages for clean
filesystems.
-
-
- -U
- Resolve user ids to user names.
-
-
- -y
- Assume a yes response to all questions asked by
fsck_lfs; this should be used with great caution as this
is a free license to continue after essentially unlimited trouble has been
encountered.
Inconsistencies checked are as follows:
- Blocks claimed by more than
one inode.
- Blocks claimed by an inode
outside the range of the filesystem.
- Incorrect link counts.
- Size checks:
- Directory size not a
multiple of DIRBLKSIZ.
- Partially truncated
file.
- Bad inode format.
- 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.
- Super Block checks:
- More blocks for inodes
than there are in the filesystem.
- Index File checks:
- “In use”
inodes on free list, or free inodes not on free list.
- Segment block counts
incorrect, or “clean” segments containing live data.
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 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_lfs are fully enumerated and
explained in Appendix A of
Fsck - The UNIX
File System Check Program.
SEE ALSO
fstab(5),
fsck(8),
newfs_lfs(8),
reboot(8)
HISTORY
The
fsck_lfs program was first made available in
NetBSD 1.4.
AUTHORS
Most of the
fsck_lfs program was taken from
fsck_ffs(8); what was not was
written by
Konrad Schroder
<
perseant@NetBSD.org>.