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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | WARNING | AUTHOR | AVAILABILITY | SEE ALSO | COLOPHON |
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BADBLOCKS(8) System Manager's Manual BADBLOCKS(8)
badblocks - search a device for bad blocks
badblocks [ -svwnfBX ] [ -b block_size ] [ -c blocks_at_once ] [
-d read_delay_factor ] [ -e max_bad_blocks ] [ -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 file system.
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. The default is 1024.
-c number of blocks
is the number of blocks which are tested at a time. The
default is 64.
-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.
-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.
-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 file system 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 file
system, 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.
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 <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>.
badblocks is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
e2fsck(8), mke2fs(8)
This page is part of the e2fsprogs (utilities for ext2/3/4
filesystems) project. Information about the project can be found
at ⟨http://e2fsprogs.sourceforge.net/⟩. It is not known how to
report bugs for this man page; if you know, please send a mail to
man-pages@man7.org. This page was obtained from the project's
upstream Git repository
⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on
2025-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2025-01-01.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
E2fsprogs version 1.47.2 January 2025 BADBLOCKS(8)
Pages that refer to this page: e2fsck(8), mke2fs(8), mkfs(8)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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