badsect - Creates files to contain bad sectors
/usr/sbin/badsect bbdir sector...
The badsect command 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 preferable to use that method to isolate bad
blocks because the bad block forwarding makes the disk appear perfect, and
such disks can then be copied with dd(1). The technique used by badsect is
also less general than bad block forwarding, as badsect cannot make amends
for bad blocks in the i-list of file systems or in swap areas.
On some disks, adding a sector that is suddenly bad to the bad sector table
currently requires the running of the standard formatter. Thus, to deal
with a newly bad block or on disks where the drivers do not support the
bad-blocking standard, badsect can be used to good effect.
Use the badsect command on a quiet file system in the following way:
1. Mount the file system and change to its root directory.
2. Make a directory BAD there.
3. 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, as reported in console error mes-
4. 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 operation will leave the bad sectors in
only the BAD files.
The badsect command 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 fsck discovers the file, it will ask "HOLD BAD BLOCK?" An affirmative
response will cause fsck to convert the inode to a regular file containing
the bad block.
If more than one of the sectors comprised by a file system fragment are
bad, you should specify only one to badsect, as the blocks in the bad sec-
tor files cover all the sectors in a file system fragment.
The badsect command 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.