path: root/Documentation/device-mapper/dm-raid.txt
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diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index 946c73342cd..1c184495716 100644
--- a/Documentation/device-mapper/dm-raid.txt
+++ b/Documentation/device-mapper/dm-raid.txt
@@ -27,6 +27,10 @@ The target is named "raid" and it accepts the following parameters:
- rotating parity N (right-to-left) with data restart
raid6_nc RAID6 N continue
- rotating parity N (right-to-left) with data continuation
+ raid10 Various RAID10 inspired algorithms chosen by additional params
+ - RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
+ - RAID1E: Integrated Adjacent Stripe Mirroring
+ - and other similar RAID10 variants
Reference: Chapter 4 of
@@ -59,6 +63,28 @@ The target is named "raid" and it accepts the following parameters:
logical size of the array. The bitmap records the device
synchronisation state for each region.
+ [raid10_copies <# copies>]
+ [raid10_format near]
+ These two options are used to alter the default layout of
+ a RAID10 configuration. The number of copies is can be
+ specified, but the default is 2. There are other variations
+ to how the copies are laid down - the default and only current
+ option is "near". Near copies are what most people think of
+ with respect to mirroring. If these options are left
+ unspecified, or 'raid10_copies 2' and/or 'raid10_format near'
+ are given, then the layouts for 2, 3 and 4 devices are:
+ 2 drives 3 drives 4 drives
+ -------- ---------- --------------
+ A1 A1 A1 A1 A2 A1 A1 A2 A2
+ A2 A2 A2 A3 A3 A3 A3 A4 A4
+ A3 A3 A4 A4 A5 A5 A5 A6 A6
+ A4 A4 A5 A6 A6 A7 A7 A8 A8
+ .. .. .. .. .. .. .. .. ..
+ The 2-device layout is equivalent 2-way RAID1. The 4-device
+ layout is what a traditional RAID10 would look like. The
+ 3-device layout is what might be called a 'RAID1E - Integrated
+ Adjacent Stripe Mirroring'.
<#raid_devs>: The number of devices composing the array.
Each device consists of two entries. The first is the device
containing the metadata (if any); the second is the one containing the