NAME
badsect —
create files to contain bad
sectors
SYNOPSIS
badsect |
bbdir sector ... |
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.
If a driver supports the bad blocking standard, it is much more 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 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 the bad sector, and whose name is the bad
sector number. When it is discovered by fsck, it will ask
“HOLD BAD BLOCK?” A positive response
will cause fsck 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
HISTORY
The badsect command appeared in
4.1BSD.
BUGS
If more than one sector which comprises a file system fragment is
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.