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

     badsect - create files to contain bad sectors

     badsect bbdir sector ...

     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

     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.

     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.


     The badsect utility appeared in 4.1BSD.

     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.

FreeBSD 11.0-PRERELEASE          June 5, 1993          FreeBSD 11.0-PRERELEASE


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