diff options
Diffstat (limited to 'Documentation/device-mapper')
| -rw-r--r-- | Documentation/device-mapper/dm-raid.txt | 26 | ||||
| -rw-r--r-- | Documentation/device-mapper/striped.txt | 7 | ||||
| -rw-r--r-- | Documentation/device-mapper/thin-provisioning.txt | 24 |
3 files changed, 52 insertions, 5 deletions
diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt index 946c73342cde..1c1844957166 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 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 diff --git a/Documentation/device-mapper/striped.txt b/Documentation/device-mapper/striped.txt index f34d3236b9da..45f3b91ea4c3 100644 --- a/Documentation/device-mapper/striped.txt +++ b/Documentation/device-mapper/striped.txt @@ -9,15 +9,14 @@ devices in parallel. Parameters: <num devs> <chunk size> [<dev path> <offset>]+ <num devs>: Number of underlying devices. - <chunk size>: Size of each chunk of data. Must be a power-of-2 and at - least as large as the system's PAGE_SIZE. + <chunk size>: Size of each chunk of data. Must be at least as + large as the system's PAGE_SIZE. <dev path>: Full pathname to the underlying block-device, or a "major:minor" device-number. <offset>: Starting sector within the device. One or more underlying devices can be specified. The striped device size must -be a multiple of the chunk size and a multiple of the number of underlying -devices. +be a multiple of the chunk size multiplied by the number of underlying devices. Example scripts diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt index f5cfc62b7ad3..30b8b83bd333 100644 --- a/Documentation/device-mapper/thin-provisioning.txt +++ b/Documentation/device-mapper/thin-provisioning.txt @@ -231,6 +231,9 @@ i) Constructor no_discard_passdown: Don't pass discards down to the underlying data device, but just remove the mapping. + read_only: Don't allow any changes to be made to the pool + metadata. + Data block size must be between 64KB (128 sectors) and 1GB (2097152 sectors) inclusive. @@ -239,7 +242,7 @@ ii) Status <transaction id> <used metadata blocks>/<total metadata blocks> <used data blocks>/<total data blocks> <held metadata root> - + [no_]discard_passdown ro|rw transaction id: A 64-bit number used by userspace to help synchronise with metadata @@ -257,6 +260,21 @@ ii) Status held root. This feature is not yet implemented so '-' is always returned. + discard_passdown|no_discard_passdown + Whether or not discards are actually being passed down to the + underlying device. When this is enabled when loading the table, + it can get disabled if the underlying device doesn't support it. + + ro|rw + If the pool encounters certain types of device failures it will + drop into a read-only metadata mode in which no changes to + the pool metadata (like allocating new blocks) are permitted. + + In serious cases where even a read-only mode is deemed unsafe + no further I/O will be permitted and the status will just + contain the string 'Fail'. The userspace recovery tools + should then be used. + iii) Messages create_thin <dev id> @@ -329,3 +347,7 @@ regain some space then send the 'trim' message to the pool. ii) Status <nr mapped sectors> <highest mapped sector> + + If the pool has encountered device errors and failed, the status + will just contain the string 'Fail'. The userspace recovery + tools should then be used. |