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BADSECT(8)									       BADSECT(8)

       badsect - create files to contain bad sectors

       /sbin/badsect 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 tech-
       nique 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.

       Adding  a sector which is suddenly bad to the bad sector table currently requires the run-
       ning of the standard DEC formatter, as UNIX does not supply formatters.	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 and change into it.  Run
       badsect giving as argument all the bad sectors you  wish  to  add.   (The  sector  numbers
       should  be  given  as  physical disk sectors relative to the beginning of the file system,
       exactly as the system reports the 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 (after tak-
       ing  into  account the filesystem's block size), creating a regular file whose first block
       address is the block containing bad sector and whose name is the bad sector  number.   The
       file has 0 length, but the check programs will still consider it to contain the block con-
       taining the sector.  This has the pleasant effect that the sector is completely inaccessi-
       ble to the containing file system since it is not available by accessing the file.

       mknod(2), bad144(8), fsck(8)

       If  both  sectors which comprise a (1024 byte) disk block are bad, you should specify only
       one of them to badsect, as the blocks in the bad sector files actually  cover  both  (bad)
       disk sectors.

       On  the	PDP-11,  only  sector number less than 131072 may be specified on 1024-byte block
       filesystems, 65536 on 512-byte block filesystems.  This is because only	a  short  int  is
       passed to the system from mknod.

3rd Berkeley Distribution							       BADSECT(8)
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