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OpenDarwin 7.2.1 - man page for badsect (opendarwin section 8)

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

     badsect -- create files to contain bad sectors

     /etc/badsect bbdir sector ...

     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;
     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 directory BAD there.  Run badsect giving as argu-
     ment 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 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 it will ask ``HOLD BAD BLOCK ?'' A
     positive response will cause fsck to convert the inode to a regular file containing the bad

     bad144(8), fsck(8), format(8)

     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.

     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.

     The badsect command appeared in 4.1BSD.

4th Berkeley Distribution		   June 5, 1993 		4th Berkeley Distribution

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