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Diffstat (limited to '')
| -rw-r--r-- | Documentation/device-mapper/era.rst (renamed from Documentation/device-mapper/era.txt) | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/Documentation/device-mapper/era.txt b/Documentation/device-mapper/era.rst index 3c6d01be3560..90dd5c670b9f 100644 --- a/Documentation/device-mapper/era.txt +++ b/Documentation/device-mapper/era.rst @@ -1,3 +1,7 @@ +====== +dm-era +====== + Introduction ============ @@ -14,12 +18,14 @@ coherency after rolling back a vendor snapshot. Constructor =========== - era <metadata dev> <origin dev> <block size> +era <metadata dev> <origin dev> <block size> - metadata dev : fast device holding the persistent metadata - origin dev : device holding data blocks that may change - block size : block size of origin data device, granularity that is - tracked by the target + ================ ====================================================== + metadata dev fast device holding the persistent metadata + origin dev device holding data blocks that may change + block size block size of origin data device, granularity that is + tracked by the target + ================ ====================================================== Messages ======== @@ -49,14 +55,16 @@ Status <metadata block size> <#used metadata blocks>/<#total metadata blocks> <current era> <held metadata root | '-'> -metadata block size : Fixed block size for each metadata block in - sectors -#used metadata blocks : Number of metadata blocks used -#total metadata blocks : Total number of metadata blocks -current era : The current era -held metadata root : The location, in blocks, of the metadata root - that has been 'held' for userspace read - access. '-' indicates there is no held root +========================= ============================================== +metadata block size Fixed block size for each metadata block in + sectors +#used metadata blocks Number of metadata blocks used +#total metadata blocks Total number of metadata blocks +current era The current era +held metadata root The location, in blocks, of the metadata root + that has been 'held' for userspace read + access. '-' indicates there is no held root +========================= ============================================== Detailed use case ================= @@ -88,7 +96,7 @@ Memory usage The target uses a bitset to record writes in the current era. It also has a spare bitset ready for switching over to a new era. Other than -that it uses a few 4k blocks for updating metadata. +that it uses a few 4k blocks for updating metadata:: (4 * nr_blocks) bytes + buffers |