BADSECT(8)              OpenBSD System Manager's Manual             BADSECT(8)

NAME
     badsect - create files to contain bad sectors

SYNOPSIS
     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 forwarding
     table for bad sectors to the driver.  If a driver supports the bad block-
     ing standard, it is much more 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 ar-
     eas.

     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 sup-
     port 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 re-
     ports 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 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 the bad sector, and whose name is the bad sector number.  When
     it is discovered by fsck it will ask ``HOLD BAD BLOCK?'' A positive re-
     sponse will cause fsck to convert the inode to a regular file containing
     the bad block.

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 al-
     ready in use.

SEE ALSO
     fsck(8)

HISTORY
     The badsect command appeared in 4.1BSD.

BUGS
     If more than one sector which comprises a file system fragment is 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.

OpenBSD 4.7                     August 6, 2007                               1
