4.3BSD - /usr/man/cat8/badsect.0

BADSECT(8)                                                          BADSECT(8)


NAME
       badsect - 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 ALSO
       bad144(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       April 27, 1985                      BADSECT(8)