diff options
Diffstat (limited to 'Documentation/device-mapper/cache.txt')
| -rw-r--r-- | Documentation/device-mapper/cache.txt | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt index f50470abe241..33d45ee0b737 100644 --- a/Documentation/device-mapper/cache.txt +++ b/Documentation/device-mapper/cache.txt @@ -50,14 +50,16 @@ other parameters detailed later): which are dirty, and extra hints for use by the policy object. This information could be put on the cache device, but having it separate allows the volume manager to configure it differently, - e.g. as a mirror for extra robustness. + e.g. as a mirror for extra robustness. This metadata device may only + be used by a single cache device. Fixed block size ---------------- The origin is divided up into blocks of a fixed size. This block size is configurable when you first create the cache. Typically we've been -using block sizes of 256k - 1024k. +using block sizes of 256KB - 1024KB. The block size must be between 64 +(32KB) and 2097152 (1GB) and a multiple of 64 (32KB). Having a fixed block size simplifies the target a lot. But it is something of a compromise. For instance, a small part of a block may be @@ -87,7 +89,7 @@ Migration throttling Migrating data between the origin and cache device uses bandwidth. The user can set a throttle to prevent more than a certain amount of -migration occuring at any one time. Currently we're not taking any +migration occurring at any one time. Currently we're not taking any account of normal io traffic going to the devices. More work needs doing here to avoid migrating during those peak io moments. |