BADSECT(8)BADSECT(8)NAMEbadsect - create files to contain bad sectors
SYNOPSIS
/etc/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 for‐
warding 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 direc‐
tory BAD there. Run badsect giving as argument the BAD directory fol‐
lowed 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 mes‐
sages.) Then change back to the root directory, unmount the file sys‐
tem 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) sys‐
tem 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 it will ask ``HOLD BAD BLOCK''? A posi‐
tive response will cause fsck to convert the inode to a regular file
containing the bad block.
SEE ALSObad144(8), fsck(8), format(8V)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.
BUGS
If more than one sector which comprise 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 frag‐
ment.
4th Berkeley Distribution June 24, 1990 BADSECT(8)
