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Diffstat (limited to 'Documentation/device-mapper/dm-raid.txt')
| -rw-r--r-- | Documentation/device-mapper/dm-raid.txt | 44 |
1 files changed, 37 insertions, 7 deletions
diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt index 56fb62b09fc5..b428556197c9 100644 --- a/Documentation/device-mapper/dm-raid.txt +++ b/Documentation/device-mapper/dm-raid.txt @@ -30,6 +30,7 @@ The target is named "raid" and it accepts the following parameters: raid10 Various RAID10 inspired algorithms chosen by additional params - RAID10: Striped Mirrors (aka 'Striping on top of mirrors') - RAID1E: Integrated Adjacent Stripe Mirroring + - RAID1E: Integrated Offset Stripe Mirroring - and other similar RAID10 variants Reference: Chapter 4 of @@ -64,15 +65,15 @@ The target is named "raid" and it accepts the following parameters: synchronisation state for each region. [raid10_copies <# copies>] - [raid10_format near] + [raid10_format <near|far|offset>] 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: + specified, but the default is 2. There are also three + variations to how the copies are laid down - the default + 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 @@ -85,6 +86,33 @@ The target is named "raid" and it accepts the following parameters: 3-device layout is what might be called a 'RAID1E - Integrated Adjacent Stripe Mirroring'. + If 'raid10_copies 2' and 'raid10_format far', then the layouts + for 2, 3 and 4 devices are: + 2 drives 3 drives 4 drives + -------- -------------- -------------------- + A1 A2 A1 A2 A3 A1 A2 A3 A4 + A3 A4 A4 A5 A6 A5 A6 A7 A8 + A5 A6 A7 A8 A9 A9 A10 A11 A12 + .. .. .. .. .. .. .. .. .. + A2 A1 A3 A1 A2 A2 A1 A4 A3 + A4 A3 A6 A4 A5 A6 A5 A8 A7 + A6 A5 A9 A7 A8 A10 A9 A12 A11 + .. .. .. .. .. .. .. .. .. + + If 'raid10_copies 2' and 'raid10_format offset', then the + layouts for 2, 3 and 4 devices are: + 2 drives 3 drives 4 drives + -------- ------------ ----------------- + A1 A2 A1 A2 A3 A1 A2 A3 A4 + A2 A1 A3 A1 A2 A2 A1 A4 A3 + A3 A4 A4 A5 A6 A5 A6 A7 A8 + A4 A3 A6 A4 A5 A6 A5 A8 A7 + A5 A6 A7 A8 A9 A9 A10 A11 A12 + A6 A5 A9 A7 A8 A10 A9 A12 A11 + .. .. .. .. .. .. .. .. .. + Here we see layouts closely akin to 'RAID1E - Integrated + Offset 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 @@ -142,3 +170,5 @@ Version History 1.3.0 Added support for RAID 10 1.3.1 Allow device replacement/rebuild for RAID 10 1.3.2 Fix/improve redundancy checking for RAID10 +1.4.0 Non-functional change. Removes arg from mapping function. +1.4.1 Add RAID10 "far" and "offset" algorithm support. |