Is there an open source software available for Linux that implements a
new block device based on an underlying block device (
DRBD or shared SAN) and
a distributed memory cache ?
What I'm looking for is something like
memcached for block devices. This would be useful for VMs based on cluster LVM (
clvmd), for instance.
Distributed means that each cached block is stored on only one of the nodes using that device such that the effective cache size is the sum of the cache sizes of the nodes. A block that is stored on one node and accessed from another node shall be forwarded on the network without accessing the underlying block device.
The cache should be write-through: Only reads should be cached, but writes should be saved (mirrored) in the cache in order to support subsequent reads.
Or should I better ask this question on software-recommendations ?