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.