Patent ID: 8838903

Claim:
A hierarchical data storage system comprising: a random access memory (RAM) receiving all initial memory writes for the hierarchical data storage system; a first non-volatile storage medium; and a controller including a ranking engine tracking counts of only data writes for data in the RAM and only data writes for same data in the first non-volatile storage medium; wherein the RAM and the first non-volatile storage medium is associated with a pre-set capacity threshold, and the controller, upon the RAM reaching a first pre-set capacity threshold, identifies, based on the counts, one or more first blocks of first data as lowest write count to the RAM, copies the first data in the one or more first blocks to the first non-volatile storage medium, and marks the one or more first blocks as available for new data writes, and the controller, upon the first non-volatile storage medium reaching a second pre-set capacity threshold, identifies, based on the counts, one or more second blocks of second data as lowest write count to the first non-volatile storage medium, and marks the one or more second blocks as available for new data writes from the RAM.