NAME
badsect —
create files to contain bad
sectors
SYNOPSIS
DESCRIPTION
badsect makes a file to contain a bad sector. Normally, bad
sectors are made inaccessible by the standard formatter, which provides a
forwarding table for bad sectors to the driver; see
bad144(8) for details. If a
driver supports the bad blocking standard it is much preferable to use that
method to isolate bad blocks, since the bad block forwarding makes the pack
appear perfect, and such packs can then be copied with
dd(1). The technique used by this
program is also less general than bad block forwarding, as
badsect can't make amends for bad blocks in the i-list of
file systems or in swap areas.
On some disks, adding a sector which is suddenly bad to the bad sector table
currently requires the running of the standard DEC formatter. Thus to deal
with a newly bad block or on disks where the drivers do not support the
bad-blocking standard
badsect may be used to good effect.
badsect is used on a quiet file system in the following way:
First mount the file system, and change to its root directory. Make a
directory
BAD
there. Run
badsect
giving as argument the
BAD directory followed by all the
bad sectors you wish to add. The sector numbers must be relative to the
beginning of the file system, but this is not hard as the system reports
relative sector numbers in its console error messages. Then change back to the
root directory, unmount the file system and run
fsck(8) on the file system. The
bad sectors should show up in two files or in the bad sector files and the
free list. Have
fsck(8) remove
files containing the offending bad sectors, but
do not have
it remove the
BAD/nnnnn files. This will
leave the bad sectors in only the
BAD
files.
badsect works by giving the specified sector numbers in a
mknod(2) system call, creating an
illegal file whose first block address is the block containing bad sector and
whose name is the bad sector number. When it is discovered by
fsck(8) it will ask
“
HOLD BAD BLOCK ?
” A positive response
will cause
fsck(8) to convert the
inode to a regular file containing the bad block.
DIAGNOSTICS
badsect refuses to attach a block that resides in a critical
area or is out of range of the file system. A warning is issued if the block
is already in use.
SEE ALSO
bad144(8),
fsck(8)
HISTORY
The
badsect command appeared in
4.1BSD.
BUGS
If more than one of the sectors in a file system fragment are bad, you should
specify only one of them to
badsect, as the blocks in the
bad sector files actually cover all the sectors in a file system
fragment.