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       badblocks - search a device for bad blocks


       badblocks  [  -svwnf  ]  [  -b  block-size ] [ -c blocks_at_once ] [ -e
       max_bad_blocks ] [ -d read_delay_factor  ]  [  -i  input_file  ]  [  -o
       output_file ] [ -p num_passes ] [ -t test_pattern ] device [ last-block
       ] [ first-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.
       first-block is an optional  parameter  specifying  the  starting  block
       number 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
       properly  specified,  since  the  block numbers which are generated are
       very dependent on the block size in use by the  filesystem.   For  this
       reason,  it  is  strongly  recommended  that  users  not  run badblocks
       directly, but rather use  the  -c  option  of  the  e2fsck  and  mke2fs


       -b block-size
              Specify the size of blocks in bytes.  The default is 1024.

       -c number of blocks
              is the number of blocks which are tested at a time.  The default
              is 64.

       -e max bad block count
              Specify a maximum number of bad blocks before aborting the test.
              The  default  is 0, meaning the test will continue until the end
              of the test range is reached.

       -d read delay factor
              This parameter, if passed and non-zero, will cause bad blocks to
              sleep  between  reads if there were no errors encountered in the
              read operation; the delay will be calculated as a percentage  of
              the  time  it  took  for  the read operation to be performed. In
              other words, a value of 100 will cause each read to  be  delayed
              by  the  amount  the  previous  read took, and a value of 200 by
              twice the amount.

       -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
              filesystem  even  if  it  is  mounted  read-only.   This  can be
              overridden using the -f flag, but should almost  never  be  used
              ---  if you think you're smarter than the badblocks program, you
              almost certainly 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
              Read a list of already existing  known  bad  blocks.   Badblocks
              will  skip  testing these blocks since they are known to be bad.
              If input_file is specified as "-", the list will  be  read  from
              the  standard input.  Blocks listed in this list will be omitted
              from the list of new bad blocks produced on the standard  output
              or in the output file.  The -b option of dumpe2fs(8) can be used
              to retrieve the list  of  blocks  currently  marked  bad  on  an
              existing  filesystem,  in  a  format  suitable for use with this

       -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.

       -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
              discovered in num_passes consecutive scans of the disk.  Default
              is 0, meaning badblocks will exit after the first pass.

       -s     Show  the  progress  of the scan by writing out rough percentage
              completion of the current badblocks pass over  the  disk.   Note
              that  badblocks  may  do  multiple test passes over the disk, in
              particular if the -p or -w option is requested by the user.

       -t test_pattern
              Specify a test pattern to be read (and written) to disk  blocks.
              The  test_pattern  may  either  be a numeric value between 0 and
              ULONG_MAX-1 inclusive, or the  word  "random",  which  specifies
              that  the block should be filled with a random bit pattern.  For
              read/write (-w) and non-destructive (-n) modes, one or more test
              patterns  may  be specified by specifying the -t option for each
              test pattern desired.  For read-only mode only a single  pattern
              may  be specified and it may not be "random".  Read-only testing
              with a pattern assumes that the specified pattern has previously
              been  written to the disk - if not, large numbers of blocks will
              fail verification.  If multiple patterns are specified then  all
              blocks  will be tested with one pattern before proceeding to the
              next pattern.

       -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.

       -X     Internal flag only to be used by e2fsck(8)  and  mke2fs(8).   It
              bypasses the exclusive mode in-use device safety check.


       Never use the -w option on a device containing an existing file system.
       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.

       The -e option will cause badblocks to output a possibly incomplete list
       of  bad  blocks.  Therefore  it  is recommended to use it only when one
       wants to know if there are any bad blocks at all on the device, and not
       when the list of bad blocks is wanted.


       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)