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BADBLOCKS
!!!BADBLOCKS
NAME
SYNOPSIS
DESCRIPTION
OPTIONS
WARNING
AUTHOR
AVAILABILITY
SEE ALSO
----
!!NAME


badblocks - search a device for bad blocks
!!SYNOPSIS


__badblocks__ [[ __-svwnf__ ] [[ __-b__
''block-size'' ] [[ __-c__ ''blocks_at_once'' ] [[
__-i__ ''input_file'' ] [[ __-o__ ''output_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 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 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
__


__-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; even a
non-destructive test can damage a mounted filesystem. 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 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
''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
__
!!AVAILABILITY


__badblocks__ is part of the e2fsprogs package and is
available from
http://e2fsprogs.sourceforge.net.
!!SEE ALSO


__e2fsck__(8), __mke2fs__(8)
----
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Version 1, saved on Monday, June 3, 2002 6:56:34 pm by "perry"
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