badsect(8)

NAME

badsect - create files to contain bad sectors

SYNOPSIS

badsect bbdir sector ...

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 directo

ry. Make a
directory BAD there. Run badsect giving as argument the BAD

directory
followed by all the bad sectors you wish to add. (The sec

tor 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 frag

ment 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.

BSD June 5, 1993

BSD