International Business Machines Corporation
Cache management using favored volumes and a multiple tiered cache memory

Abstract:

A method for demoting a selected storage element from a cache memory includes storing favored and non-favored storage elements within a higher performance portion and lower performance portion of the cache memory. The favored storage elements are retained in the cache memory longer than the non-favored storage elements. The method maintains a first favored LRU list and a first non-favored LRU list, associated with the favored and non-favored storage elements stored within the higher performance portion of the cache. The method selects a favored or non-favored storage element to be demoted from the higher performance portion of the cache memory according to life expectancy and residency of the oldest favored and non-favored storage elements in the first LRU lists. The method demotes the selected from the higher performance portion of the cache to the lower performance portion of the cache, or to the data storage devices, according to a cache demotion policy. A corresponding storage controller and computer program product are also disclosed.