.SH SYNOPSIS
.B badblocks
[
-.B \-svwn
+.B \-svwnfBX
]
[
.B \-b
.I blocks_at_once
]
[
+.B \-e
+.I max_bad_blocks
+]
+[
+.B \-d
+.I read_delay_factor
+]
+[
.B \-i
.I input_file
]
.B \-p
.I num_passes
]
+[
+.B \-t
+.I test_pattern
+]
.I device
[
-.I blocks-count
+.I last-block
] [
-.I start-block
+.I first-block
]
.SH DESCRIPTION
.B badblocks
.I device
is the special file corresponding to the device (e.g
.IR /dev/hdc1 ).
-.I blocks-count
-is the number of blocks on the device; if it is not specified, the size
-of the device is used as a default.
-.I 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.
+.I 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.
+.I 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.
+.PP
+.B Important note:
+If the output of
+.B badblocks
+is going to be fed to the
+.B e2fsck
+or
+.B 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
+.B not
+run
+.B badblocks
+directly, but rather use the
+.B \-c
+option of the
+.B e2fsck
+and
+.B mke2fs
+programs.
.SH OPTIONS
.TP
.BI \-b " block-size"
-Specify the size of blocks in bytes.
+Specify the size of blocks in bytes. The default is 1024.
.TP
.BI \-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
-.B badblocks
-but also will increase its memory usage.
-.B 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,
+is the number of blocks which are tested at a time. The default is 64.
+.TP
+.BI \-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.
+.TP
+.BI \-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.
+.TP
+.B \-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
+.B \-f
+flag, but should almost never be used --- if you think you're smarter
+than the
.B 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.
+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.
.TP
.BI \-i " input_file"
Read a list of already existing known bad blocks.
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.
.TP
+.B \-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
+.B \-w
+option, as they are mutually exclusive.
+.TP
.BI \-o " output_file"
Write the list of bad blocks to the specified file. Without this option,
.B badblocks
.B badblocks
will exit after the first pass.
.TP
-.B \-n
-Use non-destructive read-write mode.
-.TP
.B \-s
-Show the progress of the scan by writing out the block numbers as they
-are checked.
+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
+.B \-p
+or
+.B \-w
+option is requested by the user.
+.TP
+.BI \-t " test_pattern"
+Specify a test pattern to be read (and written) to disk blocks. The
+.I 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 (\fB-w\fR) and non-destructive (\fB-n\fR) modes,
+one or more test patterns may be specified by specifying the
+.B -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.
.TP
.B \-v
-Verbose mode.
+Verbose mode. Will write the number of read errors, write errors and data-
+corruptions to stderr.
.TP
.B \-w
Use write-mode test. With this option,
.B 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.
+every block of the device, reading every block and comparing the contents.
+This option may not be combined with the
+.B \-n
+option, as they are mutually exclusive.
+.TP
+.B \-B
+Use buffered I/O and do not use Direct I/O, even if it is available.
+.TP
+.B \-X
+Internal flag only to be used by
+.BR e2fsck (8)
+and
+.BR mke2fs (8).
+It bypasses the exclusive mode in-use device safety check.
.SH WARNING
Never use the
.B \-w
-option on an device containing an existing file system.
+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
.B \-n
-option. It is slower, but it will preserve your data.
+option instead. It is slower, but it will preserve your data.
+.PP
+The
+.B \-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.
.SH AUTHOR
.B badblocks
was written by Remy Card <Remy.Card@linux.org>. Current maintainer is
implemented by David Beattie <dbeattie@softhome.net>.
.SH AVAILABILITY
.B badblocks
-is part of the e2fsprogs package and is available for anonymous
-ftp from tsx-11.mit.edu in /pub/linux/packages/ext2fs.
+is part of the e2fsprogs package and is available from
+http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
.BR e2fsck (8),
.BR mke2fs (8)
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff