1BADBLOCKS(8) System Manager's Manual BADBLOCKS(8)
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6 badblocks - search a device for bad blocks
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9 badblocks [ -svwnfBX ] [ -b block_size ] [ -c blocks_at_once ] [ -d
10 read_delay_factor ] [ -e max_bad_blocks ] [ -i input_file ] [ -o out‐
11 put_file ] [ -p num_passes ] [ -t test_pattern ] device [ last_block ]
12 [ first_block ]
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15 badblocks is used to search for bad blocks on a device (usually a disk
16 partition). device is the special file corresponding to the device
17 (e.g /dev/hdc1). last_block is the last block to be checked; if it is
18 not specified, the last block on the device is used as a default.
19 first_block is an optional parameter specifying the starting block num‐
20 ber for the test, which allows the testing to start in the middle of
21 the disk. If it is not specified the first block on the disk is used
22 as a default.
23 Important note: If the output of badblocks is going to be fed to the
25 e2fsck or mke2fs programs, it is important that the block size is prop‐
26 erly specified, since the block numbers which are generated are very
27 dependent on the block size in use by the filesystem. For this reason,
28 it is strongly recommended that users not run badblocks directly, but
29 rather use the -c option of the e2fsck and mke2fs programs.
30
32 -b block_size
33 Specify the size of blocks in bytes. The default is 1024.
34 -c number of blocks
36 is the number of blocks which are tested at a time. The default
37 is 64.
38 -d read delay factor
40 This parameter, if passed and non-zero, will cause bad blocks to
41 sleep between reads if there were no errors encountered in the
42 read operation; the delay will be calculated as a percentage of
43 the time it took for the read operation to be performed. In
44 other words, a value of 100 will cause each read to be delayed
45 by the amount the previous read took, and a value of 200 by
46 twice the amount.
47 -e max bad block count
49 Specify a maximum number of bad blocks before aborting the test.
50 The default is 0, meaning the test will continue until the end
51 of the test range is reached.
52 -f Normally, badblocks will refuse to do a read/write or a non-
54 destructive test on a device which is mounted, since either can
55 cause the system to potentially crash and/or damage the filesys‐
56 tem even if it is mounted read-only. This can be overridden
57 using the -f flag, but should almost never be used --- if you
58 think you're smarter than the badblocks program, you almost cer‐
59 tainly aren't. The only time when this option might be safe to
60 use is if the /etc/mtab file is incorrect, and the device really
61 isn't mounted.
62 -i input_file
64 Read a list of already existing known bad blocks. Badblocks
65 will skip testing these blocks since they are known to be bad.
66 If input_file is specified as "-", the list will be read from
67 the standard input. Blocks listed in this list will be omitted
68 from the list of new bad blocks produced on the standard output
69 or in the output file. The -b option of dumpe2fs(8) can be used
70 to retrieve the list of blocks currently marked bad on an exist‐
71 ing filesystem, in a format suitable for use with this option.
72 -n Use non-destructive read-write mode. By default only a non-
74 destructive read-only test is done. This option must not be
75 combined with the -w option, as they are mutually exclusive.
76 -o output_file
78 Write the list of bad blocks to the specified file. Without
79 this option, badblocks displays the list on its standard output.
80 The format of this file is suitable for use by the -l option in
81 e2fsck(8) or mke2fs(8).
82 -p num_passes
84 Repeat scanning the disk until there are no new blocks discov‐
85 ered in num_passes consecutive scans of the disk. Default is 0,
86 meaning badblocks will exit after the first pass.
87 -s Show the progress of the scan by writing out rough percentage
89 completion of the current badblocks pass over the disk. Note
90 that badblocks may do multiple test passes over the disk, in
91 particular if the -p or -w option is requested by the user.
92 -t test_pattern
94 Specify a test pattern to be read (and written) to disk blocks.
95 The test_pattern may either be a numeric value between 0 and
96 ULONG_MAX-1 inclusive, or the word "random", which specifies
97 that the block should be filled with a random bit pattern. For
98 read/write (-w) and non-destructive (-n) modes, one or more test
99 patterns may be specified by specifying the -t option for each
100 test pattern desired. For read-only mode only a single pattern
101 may be specified and it may not be "random". Read-only testing
102 with a pattern assumes that the specified pattern has previously
103 been written to the disk - if not, large numbers of blocks will
104 fail verification. If multiple patterns are specified then all
105 blocks will be tested with one pattern before proceeding to the
106 next pattern.
107 -v Verbose mode. Will write the number of read errors, write
109 errors and data- corruptions to stderr.
110 -w Use write-mode test. With this option, badblocks scans for bad
112 blocks by writing some patterns (0xaa, 0x55, 0xff, 0x00) on
113 every block of the device, reading every block and comparing the
114 contents. This option may not be combined with the -n option,
115 as they are mutually exclusive.
116 -B Use buffered I/O and do not use Direct I/O, even if it is avail‐
118 able.
119 -X Internal flag only to be used by e2fsck(8) and mke2fs(8). It
121 bypasses the exclusive mode in-use device safety check.
122
124 Never use the -w option on a device containing an existing file system.
125 This option erases data! If you want to do write-mode testing on an
126 existing file system, use the -n option instead. It is slower, but it
127 will preserve your data.
128 The -e option will cause badblocks to output a possibly incomplete list
130 of bad blocks. Therefore it is recommended to use it only when one
131 wants to know if there are any bad blocks at all on the device, and not
132 when the list of bad blocks is wanted.
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135 badblocks was written by Remy Card <Remy.Card@linux.org>. Current
136 maintainer is Theodore Ts'o <tytso@alum.mit.edu>. Non-destructive
137 read/write test implemented by David Beattie <dbeattie@softhome.net>.
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140 badblocks is part of the e2fsprogs package and is available from
141 http://e2fsprogs.sourceforge.net.
142
144 e2fsck(8), mke2fs(8)
145E2fsprogs version 1.44.6 March 2019 BADBLOCKS(8)