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RedHat 9 (Linux i386) - man page for badblocks (redhat section 8)

BADBLOCKS(8)									     BADBLOCKS(8)

NAME
       badblocks - search a device for bad blocks

SYNOPSIS
       badblocks  [  -svwnf ] [ -b block-size ] [ -c blocks_at_once ] [ -i input_file ] [ -o out-
       put_file ] [ -p num_passes ] device [ last-block ] [ start-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.   start-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 spec-
       ified 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 pro-
       grams, it is important that the block size is properly 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.

OPTIONS
       -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-destructive-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 filesystem even if it is mounted read-only.  This can be  overri-
	      den  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.

       -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.

       -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.

WARNING
       Never  use  the	-w  option  on an 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.

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.source-
       forge.net.

SEE ALSO
       e2fsck(8), mke2fs(8)

E2fsprogs version 1.32			  November 2002 			     BADBLOCKS(8)


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