raid6check.8

   1 .\" -*- nroff -*-
   2 .\" Copyright Piergiorgio Sartor and others.
   3 .\"   This program is free software; you can redistribute it and/or modify
   4 .\"   it under the terms of the GNU General Public License as published by
   5 .\"   the Free Software Foundation; either version 2 of the License, or
   6 .\"   (at your option) any later version.
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   8 .TH RAID6CHECK 8 "" v1.0.0
   9 .SH NAME
  10 raid6check \- check MD RAID6 device for errors
  11 .I aka
  12 Linux Software RAID
  13
  14 .SH SYNOPSIS
  15
  16 .BI raid6check " <raid6 device> <start stripe> <number of stripes>"
  17
  18 .SH DESCRIPTION
  19 RAID6 devices in which one single component drive has errors can use
  20 the double parity in order to find out which component drive.
  21 The "raid6check" tool checks, for each stripe, the double parity
  22 consistency, reports mismatches and, if possible, which
  23 component drive has the mismatch.
  24 Since it works at stripe level, it can report different drives with
  25 mismatches at different stripes.
  26
  27 "raid6check" requires a non-degraded RAID6 MD device as first
  28 parameter, a starting stripe (usually 0) and the number of stripes
  29 to be checked.
  30 If this third parameter is also 0, it will check the array up to
  31 the end.
  32
  33 "raid6check" will start printing information about the RAID6, then
  34 for each stripe, it will report the parity rotation status.
  35 In case of parity mismatches, "raid6check" reports, if possible,
  36 which component drive could be responsible. Otherwise it reports
  37 that it is not possible to find the component drive.
  38
  39 If the given MD device is not a RAID6, "raid6check" will, of
  40 course, not continue.
  41
  42 If the RAID6 MD device is degraded, "raid6check" will report
  43 an error and it will not proceed further.
  44
  45 No write operations are performed on the array or the components.
  46 Furthermore, the checked array can be online and in use during
  47 the operation of "raid6check".
  48
  49 .SH EXAMPLES
  50
  51 .B "  raid6check /dev/md0 0 0"
  52 .br
  53 This will check /dev/md0 from start to end.
  54
  55 .B "  raid6check /dev/md3 0 1"
  56 .br
  57 This will check the first stripe of /dev/md3.
  58
  59 .B "  raid6check /dev/md1 1000 0"
  60 .br
  61 This will check /dev/md1 from stripe 1000 up to the end.
  62
  63 .B "  raid6check /dev/m127 128 256"
  64 .br
  65 This will check 256 stripes of /dev/md127 starting from stripe 128.
  66
  67 .B "  raid6check /dev/md0 0 0 | grep -i error > md0_err.log"
  68 .br
  69 This will check /dev/md0 completely and create a log file only
  70 with errors, if any.
  71
  72 .SH FILES
  73
  74 "raid6check" uses directly the component drives as found in /dev.
  75 Furthermore, the sysfs interface is needed in order to find out
  76 the RAID6 parameters.
  77
  78 .SH BUGS
  79 Negative parameters can lead to unexpected results.
  80
  81 It is not clear what will happen if the RAID6 MD device gets
  82 degraded during the check.
  83
  84 .PP
  85 The latest version of
  86 .I raid6check
  87 should always be available from
  88 .IP
  89 .B http://www.kernel.org/pub/linux/utils/raid/mdadm/
  90 .PP
  91 Related man pages:
  92 .PP
  93 .IR mdadm (8)
  94 .IR mdmon (8),
  95 .IR mdadm.conf (5),
  96 .IR md (4).