Sprite 1984 - 1993/Sprite 1984 - 1993.iso/man/cmds/fscheck.man

Text File | 1990-02-15 | 13.1 KB | 286 lines

' $Header: /sprite/src/cmds/fscheck/RCS/fscheck.man,v 1.6 89/08/25 22:24:31 jhh Exp $ SPRITE (Berkeley)
.so \*(]ltmac.sprite
.HS FSCHECK cmds
.BS
.SH NAME
fscheck \- perform consistency check on file system
.SH SYNOPSIS
\fBfscheck -dev \fIdevice\fP -part \fIpartition\fP [\fIoptions\fR]
.SH OPTIONS
.IP "\fB\-dev\fI device\fR" 14
\fIDevice\fP is the root name of a device, i.e. rxy0, rsd1, rsb0
.IP "\fB\-part\fI partition\fR" 14
\fIPartition\fP is a letter indicating a partition, i.e. a, b, c, d, e, f, g.
.IP "\fB\-dir\fI devDir\fR" 14
\fIDevDir\fR is an alternate directory in which to find the device file
named by concatenating \fIDevice\fR and \fIPartition\fR.  The default
directory name is ``/dev/``.
.IP "\fB\-initialPart\fI firstPartName\fR" 14
\fIfirstPartName\fP is the name of the initial partition on the disk
which contains basic disk geometry information.  The default is partition
``a''.
.IP "\fB\-write\fR" 14
Write the disk when errors are encountered and fixed.  The default is to
not write the disk.
.IP "\fB\-silent\fR" 14
Don't say anything unless there is an error.
.IP "\fB\-verbose\fR" 14
Output verbose information about errors.  The default is to print out
terse information.
.IP "\fB\-incVersion\fR" 14
If the domain was not written back properly on system shutdown then all
version numbers will be incremented.
.IP "\fB\-fixRoot\fR" 14
Re-create a missing or corrupted root directory.
.IP "\fB\-clear\fR" 14
Clear the domain number field stored in the summary sector.
.IP "\fB\-hostID\fI id\fR" 14
Update the host ID in the disk header. If \fIid\fR is not 0 then it is used
as the host id to put in the header. If \fIid\fR equals 0 then one of two
values are used as the host id.  If the device server is the local host
then the kernel's internal idea of its host id is used, otherwise the
device server's id is used.
.IP "\fB\-badBlock\fR" 14
Initialize the bad block file descriptor.
.IP "\fB\-outputFile\fI outputFile\fR" 14
All output to stdout and stderr is also appended to
\fIoutputFile\fR.
.IP "\fB\-bufferSize\fI size\fR" 14
Set the size of the buffer associated with \fIoutputFile\fR to \fIsize\fR bytes.
Default is to use whatever buffer is provided by the stdio library.
This option has no effect if the \fB\-outputFile\fR option is not used.
.IP "\fB\-rootPart\fR" 14
This option controls the output to a file. If the \fB\-outputFile\fR option
is not given then this option has no effect.
Otherwise, the output is stored in a buffer and only written to the
file when the program exits.
This allows the output to be written to a file on the partition being checked
(usually the output is written to the root partition).
The file IO in this case is very primative and restrictive. The output file
must be in the root directory and must exist prior to running \fBfscheck\fR.
If the size of the output exceeds the size of the file or if it exceeds the
size of the direct data blocks then it will be truncated. If the output
exceeds the size of the internal buffer it will be truncated
(see \fB\-bufferSize\fR ).
If the output is smaller than the size of the file, the remaining part of
the file will be filled with null characters.
Any file produced by this option will have a decimal number in the first
line which represents the number of bytes in the file. This is used by
\fBfscheck\fR to calculate the starting point for appending.
The output file can be reset by either setting the first number to 0 or by
overwriting the file with null characters.
.IP "\fB\-heapLimit\fI size\fR" 14
Program will not allocate more than \fIsize\fR bytes of memory. Default is to
allocate as much as is needed.
.IP "\fB\-delete\fR" 14
If a data block is shared by more than one file, delete it from all but one
of the files. The default is to make a copy of the block for each file
sharing the original.
.IP "\fB\-readBlock\fI count\fR" 14
Read count blocks at a time when reading the file descriptors.
Currently this does not provide better performance due to limitations in the
disk interface library.
.IP "\fB\-debug\fR" 14
Print out debugging information.
.IP "\fB\-bitmapVerbose\fR" 14
Print out lots and lots of information about errors in the bitmaps.
.IP "\fB\-numReboot\fI count\fR" 14
Number of consecutive times to reboot before returning a warning indication.
.IP "\fB\-clearFixCount\fR" 14
Clear consecutive fix counter.
.BE

.SH DESCRIPTION
.LP
This program will perform a consistency check on a file system.  By default
it will report inconsistencies but won't repair them.  If the \fB\-write\fP
option
is used then it will repair any inconsistencies by modifying the disk as
necessary.
.LP
This program performs the following consistency checks:
.IP 1. 5
It makes sure that the file descriptor allocation bit map agrees with the
status information kept in each file descriptor.  If necessary it will correct
the bit map.
.IP 2. 5
It confirms that data-block and indirect-block pointers are valid.  If a
pointer is invalid then the pointer is set to NIL and the file size is
adjusted as necessary to reflect the new size of the file.
.IP 3. 5
It recreates the data block allocation bit map based on information in
the file descriptors and indirect blocks.
.IP 4. 5
It checks for blocks that are allocated to more than one file.
If a block is multiply allocated then copies of the block are made and
all but one of
the files is corrected to use a copy.
If the \fB\-delete\fR option is given, or if only a subset of the fragments in
a block are shared, then the block is given to the
lowest numbered file
descriptor and it is removed from all other files that reference it.
A special case is made of block 0. This block belongs to the root directory
and is copied (or deleted) for all other files even if the root directory
is corrupted or doesn't exist.
.IP 5. 5
It verifies that directories are of the proper format.  In order to patch
a directory, names may be deleted, the directory may be truncated,
or in the worst case the directory may be turned into a normal file.
.IP 6. 5
It puts unreferenced files into the lost+found directory.  The name of each
file in the lost+found directory is the file's file descriptor number.
.IP 7. 5
It corrects link counts and block counts in each file descriptor.
.IP 8. 5
It checks that indirect blocks contain valid pointers. If the pointers are
invalid and the block is part of a file then a hole is created,
otherwise if the
block is part of a directory then the directory is truncated.
.IP 9. 5
It checks that each file descriptor contains a valid magic number. If this is
not the case then the file descriptor is cleared and marked as unused in the
bitmap.
.IP 10. 5
It recreates the root directory if it is corrupted and the \fB\-fixRoot\fR
option is given.
.LP
By default only terse information is given about the errors in the file system.
Only the first error per file is reported.
If the \fB\-verbose\fP
option is given then more verbose information will be given.
If the \fB\-bitmapVerbose\fR option is given then differences between the
bitmaps on disk and the recreated bitmaps are printed. Since the bitmaps
on disk are not kept current use of this option is likely to produce
lots of output.
.LP
The \fBfscheck\fP program will also perform other actions depending on
the options that are specified.  If the \fB\-incVersion\fP
option is given then flags
in the file system header are checked to see if the file system
was safely written back
when it was detached or the system went down.  If it is determined that the
file system was not safely written back then the version numbers for
all files in the file system are incremented.  This will cause all
reopens of files because of recovery to fail.
.LP
If the \fB\-fixRoot\fP option is given the root directory will
be recreated if it has become corrupted.  If the root is recreated, then
any directories that have the root directory as their parent
will be inserted into the root with their file descriptor number
as their name.
Any files that used to be in the root directory will be placed in lost+found.
\fBFscheck\fR assumes that data block 0 belongs to the root directory and
will allocate this block to the directory when reconstructing it.
The \fB\-fixRoot\fR option requires reading the root directory twice, hence
it cannot be used without the \fB\-write\fR option.
.LP
The \fB\-clear\fP option should be used if the domain number field should be
cleared from the summary sector.  Each file system that is attached is
given a domain number under which it can be identified.
When a file system is attached, the system will try to attach it with the same
domain number that it was attached under last time.  This
is required to allow clients of the file system to recover when the file
system is reattached.  If the domain number field is cleared from the
summary sector, then the system will attach the file system under a domain
number of the system's choosing.
.LP
The \fB\-hostID\fP option will force the system to update the host id in the
file system header.  If the device under which the file system is being
attached is generic then the id of the host on which \fBfscheck\fP is run is
used.  Otherwise the host id specified by the device file is used.
The default is not to modify the host id.
.LP
The \fB\-badBlock\fP
option will initialize the file descriptor which points
to bad disk blocks.  Initializing it will clear out any pointers to bad
blocks that are currently in the file descriptor.
.LP
The \fB\-heapLimit\fR option can be used to place an upper limit on the
size of the program heap. This can be used to prevent paging, since paging
cannot be done at the point in the boot sequence when \fBfscheck\fR is run.
If \fBfscheck\fR cannot
complete checking the disk because of the limit then it will
do as much as it can.
This should allow multiple runs of \fBfscheck\fR to completely check the disk.
The limit is only an approximation of how large \fBfscheck\fR will grow, since
the program stack is not restricted. Therefore the limit should be set as
high as possible but it should not be set to the boundary at which
paging will occur.
If it is set too small then \fBfscheck\fR may not be
able to run
at all. Note that the \fBbufferSize\fR and \fBreadBlock\fR
options will affect the amount of heap required.
As a rule of thumb, the amount of heap space needed by \fBfscheck\fR
is proportional
to the disk size and the amount of errors on the disk.
A heap limit of 1 Mb should be sufficient for all but the most extreme cases.
.LP
Each time \fBfscheck\fR runs and finds an error in a partition, a
counter on disk
is incremented. The value of this counter is the number of consecutive
times \fBfscheck\fR has run on the partition and corrected an error.
If the counter
exceeds the value given by the \fB\-numReboot\fR option (default 4) and
if \fBfscheck\fR corrects an error, then \fBfscheck\fR will return
EXIT_NOREBOOT
instead of the standard soft error indication.
This allows higher level software to avoid infinite reboot loops.
.LP
The \fB\-clearFixCount\fR option resets the consecutive counter to 0.
.LP
Finally, the \fB\-output\fR, \fB\-bufferSize\fR and \fB\-noFlush\fR options
control the output from fscheck. The \fB\-output\fR option
allows the output from fscheck
to be put into a file as well as printed on stdout and stderr.
The \fB\-bufferSize\fR option sets the size of the IO buffer associated with
the output file.
The \fB\-noFlush\fR option prevents the buffer from being flushed until the
disk has been checked and corrected.
This allows the output to be written to the disk being checked.
If the output exceeds the size of the buffer then it is truncated to the
buffer size.
If the buffer size is exceeded in the middle of an output string, then remainder
of the string will wrap over the beginning of the buffer.
.SH EXIT CODES
.LP
\fBFscheck\fR has a large number of exit codes.
Positive values indicate that some sort of error occurred that requires
\fBfscheck\fR be run again, although an exit code of 1 indicates that the
filesystem was corrupted but was successfully corrected.
Negative error codes indicate that a serious error occurred that requires
user action before fscheck can be run again.
.IP 0 5
No errors occurred and no errors were fixed in the filesystem.
.IP 1 5
Errors were fixed in the filesystem.
.IP 2 5
\fBFscheck\fR ran out of memory before it was able to completely check the
disk. Rerunning with the same heap limit should allow \fBfscheck\fR to finish.
.IP 3 5
Errors were fixed in the filesystem and the number of consecutive times
\fBfscheck\fR has fixed this partition exceeds the limit.
.IP -1 5
An unspecified hard error occurred.
.IP -2 5
A disk read failed.
.IP -3 5
A disk write failed.
.IP -4 5
There was a problem with one of the arguments.
.IP -5 5
The heap limit is too small for \fBfscheck\fR to run. The heap limit must be
made larger before rerunning \fBfscheck\fR.
.IP -6 5
The disk is full so that duplicate blocks cannot be copied. Either delete some
stuff or rerun using the \fB\-delete\fR option.
.LP
.SH BUGS/FEATURES
.LP
Indirect blocks are always marked as in use in the bitmap, even if they contain
invalid entries. This is because the block may be in use by another file and
cannot be marked as free.
.LP
The \fB\-fixRoot\fR option cannot be used without the \fB\-write\fR option.
.SH KEYWORDS
file system, disk