Provided by: e2fsprogs_1.42-1ubuntu2_amd64 bug

NAME

       badblocks - search a device for bad blocks

SYNOPSIS

       badblocks  [ -svwnfBX ] [ -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 ]

DESCRIPTION

       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 programs.

OPTIONS

       -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 option.

       -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.   Will  write  the  number  of  read  errors, write errors and data-
              corruptions to stderr.

       -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.

       -B     Use buffered I/O and do not use Direct I/O, even if it is available.

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

WARNING

       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.

AUTHOR

       badblocks was written by Remy Card <Remy.Card@linux.org>.  Current maintainer is  Theodore
       Ts'o  <tytso@alum.mit.edu>.   Non-destructive read/write test implemented by David Beattie
       <dbeattie@softhome.net>.

AVAILABILITY

       badblocks   is   part   of   the    e2fsprogs    package    and    is    available    from
       http://e2fsprogs.sourceforge.net.

SEE ALSO

       e2fsck(8), mke2fs(8)