badblocks (8)


       badblocks - search a device for bad blocks


       badblocks  [  -svwnf  ]  [  -b  block-size ] [ -c blocks_at_once ] [ -i
       input_file ] [ -o output_file ] [ -p num_passes ] device [ last-block ]
       [ start-block ]


       badblocks  is used to search for bad blocks on a device (usually a disk
       partition).  device is the special file  corresponding  to  the  device
       (e.g  /dev/hdc1).  last-block is the last block to be checked; if it is
       not specified, the last block on the  device  is  used  as  a  default.
       start-block is an optional parameter specifying the starting block num-
       ber for the test, which allows the testing to start in  the  middle  of
       the  disk.   If it is not specified the first block on the disk is used
       as a default.

       Important note: If the output of badblocks is going to be  fed  to  the
       e2fsck or mke2fs programs, it is important that the block size is prop-
       erly specified, since the block numbers which  are  generated  is  very
       dependent  on  the block size in use.   For this reason, it is strongly
       recommended that users not run badblocks directly, but rather  use  the
       -c option of the e2fsck and mke2fs programs.


       -b block-size
              Specify the size of blocks in bytes.

       -c number of blocks
              is the number of blocks which are tested at a time.  The default
              is 16.  Increasing this number will increase the  efficiency  of
              badblocks  but  also  will increase its memory usage.  Badblocks
              needs memory proportional to the  number  of  blocks  tested  at
              once,  in  read-only  mode, proportional to twice that number in
              read-write mode, and proportional to three times that number  in
              non-destructive  read-write  mode.   If  you  set the number-of-
              blocks parameter to too high a value, badblocks will exit almost
              immediately   with  an  out-of-memory  error  "while  allocating
              buffers".  If you set it too low, however,  for  a  non-destruc-
              tive-write-mode  test, then it's possble for questionable blocks
              on an unreliable hard drive to be hidden by the effects  of  the
              hard disk track buffer.

       -f     Normally,  badblocks  will  refuse  to do a read/write or a non-
              destructive test on a device which is mounted, since either  can
              cause the system to potentially crash and/or damage the filesys-
              tem even if it is mounted  read-only.   This  can  be  overriden
              using  the  -f  flag, but should almost never be used --- if you
              think you're smarter than the badblocks program, you almost cer-
              tainly  aren't.  The only time when this option might be safe to
              use is if the /etc/mtab file is incorrect, and the device really
              isn't mounted.

       -i input_file

       -o output_file
              Write  the  list  of  bad blocks to the specified file.  Without
              this option, badblocks displays the list on its standard output.
              The  format of this file is suitable for use by the -l option in
              e2fsck(8) or mke2fs(8).

       -p num_passes
              Repeat scanning the disk until there are no new  blocks  discov-
              ered in num_passes consecutive scans of the disk.  Default is 0,
              meaning badblocks will exit after the first pass.

       -n     Use non-destructive read-write mode.  By  default  only  a  non-
              destructive  read-only  test  is  done.  This option must not be
              combined with the -w option, as they are mutually exclusive.

       -s     Show the progress of the scan by writing out the  block  numbers
              as they are checked.

       -v     Verbose mode.

       -w     Use  write-mode  test. With this option, badblocks scans for bad
              blocks by writing some patterns  (0xaa,  0x55,  0xff,  0x00)  on
              every block of the device, reading every block and comparing the
              contents.  This option may not be combined with the  -n  option,
              as they are mutually exclusive.


       Never  use  the -w option on an device containing an existing file sys-
       tem.  This option erases data!  If you want to do write-mode testing on
       an  existing file system, use the -n option instead.  It is slower, but
       it will preserve your data.


       badblocks was written  by  Remy  Card  <>.   Current
       maintainer  is  Theodore  Ts'o  <>.   Non-destructive
       read/write test implemented by David Beattie <>.


       badblocks is part of  the  e2fsprogs  package  and  is  available  from


       e2fsck(8), mke2fs(8)

E2fsprogs version 1.32           November 2002                    badblocks(8)