Item-wise simulation in a block cache where data eviction places data into comparable score in comparable section in the block cache

Abstract

Several embodiments include a method of operating a cache appliance comprising a primary memory implementing an item-wise cache and a secondary memory implementing a block cache. The cache appliance can emulate item-wise storage and eviction in the block cache by maintaining, in the primary memory, sampling data items from the block cache. The sampled items can enable the cache appliance to represent a spectrum of retention priorities. When storing a pending data item into the block cache, a comparison of the pending data item with the sampled items can enable the cache appliance to identify where to insert a block containing the pending data item. When evicting a block from the block cache, a comparison of a data item in the block with at least one of the sampled items can enable the cache appliance to determine whether to recycle/retain the data item.