1DISKSCAN(1) User Commands DISKSCAN(1)
2
6 diskscan - scan a disk for failed and near failure sectors
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9 diskscan [options...] block_device
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12 diskscan is intended to check a disk and find any bad sectors already
13 present and assess it for any possible sectors that are in the process
14 of going bad. The operation is all read-only and can cause no direct
15 damage to the data on the disk.
16 diskscan reads the entire block device and notes the time it took to
18 read a block. When there is an error it is immediately noted and also
19 when there is a higher latency to read a block. A histogram of the
20 block latency times is also given to assess the health of the disk.
21 The output of diskscan will show any serious errors or very high
23 latency and will also emit an histogram at the end of the run in the
24 form:
25 I: Validating path /dev/sdg
27 I: Opened disk /dev/sdg
28 I: Scanning disk /dev/sdg
29 Access time histogram:
30 1: 0
31 10: 0
32 100: 0
33 500: 120
34 1000: 0
35 2000: 1
36 3000: 0
37 4000: 0
38 5000: 0
39 6000: 0
40 7000: 0
41 8000: 0
42 9000: 0
43 10000: 0
44 15000: 0
45 20000: 0
46 25000: 0
47 30000: 0
48 above that: 0
49 I: Closed disk /dev/sdg
50 This means that all I/Os in this case were between 100 and 600 msec and
52 there were 120 chunks being read. Current these chunks are 1MB in size.
53
55 -v, --verbose display verbose information from the workings of the scan
56 use multiple times for increased verbosity.
57 -f, --fix Attempt to fix areas that are nearing failure. This should
59 only be attempted on an unmounted block device and never on an inuse
60 filesystem or corruption is likely.
61 -s <mode>, --scan <mode> Scan mode can be either seq or random, random
63 reduces the chance that the disk will be able spend time to recover
64 data before we try to access a sector but the seeks add noise to the
65 latency measurement. Sequential test is the default and random test is
66 still experimental with regard to its usefulness.
67 -e <size>, --size <size> Set the size in which the scan will be done,
69 this must be a multiple of the sector size which is normally 512 bytes.
70 -o <file>, --output <file> Set the output file that the scan will
72 generate. This is a JSON file with the summary and details about the
73 exceptional events found during the scan.
74 -r <file>, --raw-log <file> Set the output file for the raw log which
76 logs everything done and seen during the scan. This is a rather large
77 file but it can help get the finer details of the scan progress and the
78 disk behavior during the scan. This is too a JSON file.
79
81 badblocks(1), fsck(1)
82
84 Baruch Even \<baruch@ev-en.org>
85DiskScan 0.20 2013-10-25 DISKSCAN(1)