Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth...

[deliverable/linux.git] / Documentation / device-mapper / dm-raid.txt

diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index 946c73342cdea1c4afb23cb889828856a5e6308d..1c184495716697610d4bb41e1dde3ab60dce9e51 100644 (file)
--- 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
   http://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf
@@ -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