NAME¶
badsect —
create files to contain bad
sectors
SYNOPSIS¶
DESCRIPTION¶
The
badsect utility 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 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 cannot 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.
The
badsect utility 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.
The
badsect utility 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¶
The
badsect utility 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¶
fsck(8)
HISTORY¶
The
badsect utility appeared in
4.1BSD.
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
fragment.