122 lines
4.3 KiB
Diff
122 lines
4.3 KiB
Diff
From 2a63857e9506324ec3ef69746344de08f55e6d77 Mon Sep 17 00:00:00 2001
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From: Mingye Wang <arthur200126@gmail.com>
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Date: Sat, 20 Sep 2025 14:21:40 +0800
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Subject: [PATCH 64/74] Update raid6check man page
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This adds autorepair and manual repair modes, which have been here for about 12 years. The description of the manual repair mode can probably use more work.
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Signed-off-by: Mingye Wang <arthur200126@gmail.com>
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---
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raid6check.8 | 61 +++++++++++++++++++++++++++++++++++++---------------
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1 file changed, 44 insertions(+), 17 deletions(-)
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diff --git a/raid6check.8 b/raid6check.8
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index 8999ca89e951..f6acb288834b 100644
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--- a/raid6check.8
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+++ b/raid6check.8
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@@ -13,48 +13,72 @@ Linux Software RAID
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.SH SYNOPSIS
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-.BI raid6check " <raid6 device> <start stripe> <number of stripes>"
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+.BI raid6check " <raid6_device> <start_stripe> <number_of_stripes>"
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+.RB [ autorepair ]
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+
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+.BI raid6check " <raid6_device> " repair " <stripe> <failed_slot_1>"
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+.I "<failed_slot_2>"
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.SH DESCRIPTION
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RAID6 devices in which one single component drive has errors can use
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the double parity in order to find out which component drive.
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-The "raid6check" tool checks, for each stripe, the double parity
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-consistency, reports mismatches and, if possible, which
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+The "raid6check" tool has two modes: check mode and repair mode.
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+
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+"raid6check" requires a non-degraded RAID6 MD device as first
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+parameter. If the given MD device is not a RAID6, "raid6check" will,
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+of course, not continue.
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+
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+If the RAID6 MD device is degraded, "raid6check" will report
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+an error and it will not proceed further.
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+
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+.SS Check mode
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+In the check mode, the "raid6check" tool checks, for each stripe, the
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+double parity consistency, reports mismatches and, if possible, which
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component drive has the mismatch.
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Since it works at stripe level, it can report different drives with
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mismatches at different stripes.
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-"raid6check" requires a non-degraded RAID6 MD device as first
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-parameter, a starting stripe (usually 0) and the number of stripes
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-to be checked.
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+In addition to the MD device, "raid6check" requries a starting stripe
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+(usually 0) and the number of stripes to be checked.
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If this third parameter is also 0, it will check the array up to
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the end.
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+If the fourth parameter is "autorepair", it will overwrite single-slot
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+errors.
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"raid6check" will start printing information about the RAID6, then
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for each stripe, it will report the parity rotation status.
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In case of parity mismatches, "raid6check" reports, if possible,
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-which component drive could be responsible. Otherwise it reports
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-that it is not possible to find the component drive.
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-
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-If the given MD device is not a RAID6, "raid6check" will, of
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-course, not continue.
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+which component drive could be responsible.
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+Otherwise it reports that it is not possible to find the component drive.
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-If the RAID6 MD device is degraded, "raid6check" will report
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-an error and it will not proceed further.
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-
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-No write operations are performed on the array or the components.
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+No write operations are performed on the array or the components,
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+unless "autorepair" is specified.
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Furthermore, the checked array can be online and in use during
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the operation of "raid6check".
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+.SS Repair mode
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+In the repair mode, the "raid6check" tool checks the given stripe.
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+If inconsistencies are found, it attempts to repair the strip assuming
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+that the two given slots are incorrect.
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+
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+-1 may be used to specify parity P and -2 parity Q.
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+
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.SH EXAMPLES
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.B " raid6check /dev/md0 0 0"
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.br
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This will check /dev/md0 from start to end.
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-.B " raid6check /dev/md3 0 1"
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+.B " raid6check /dev/md3 0 1 autorepair"
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+.br
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+This will check the first stripe of /dev/md3.
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+Any error will be reported, and if single-slot, repaired.
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+
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+.B " raid6check /dev/md3 0 repair 1 -1 -2"
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.br
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This will check the first stripe of /dev/md3.
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+If any inconsistencies are found, repair is performed assuming
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+the two parities are incorrect.
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.B " raid6check /dev/md1 1000 0"
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.br
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@@ -76,7 +100,10 @@ Furthermore, the sysfs interface is needed in order to find out
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the RAID6 parameters.
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.SH BUGS
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-Negative parameters can lead to unexpected results.
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+Negative stripe parameters can lead to unexpected results due to
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+strtoull.
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+(Negative slot numbers should work for Q [-1] and P [-2] but
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+currently involve compiler-defined behavior.)
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It is not clear what will happen if the RAID6 MD device gets
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degraded during the check.
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--
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2.50.1
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