1. An apparatus, comprising: non-transitory storage media configured as a cache associated with a physical computing machine that shares access to a block storage device with at least one other physical computing machine; a caching logic associated with the physical computing machine, the caching logic configured to cache data in the cache, wherein the caching logic caches data stored in a delegated range of memory blocks and does not cache data stored outside of the delegated range of memory blocks; and a block delegation logic configured to assign a caching right for the delegated range of memory blocks in the block storage device to the caching logic, wherein the caching right is an exclusive right granted to the caching logic.