Adjusting active cache size based on cache usage

A system coupled to a storage having tracks, comprising:

• a processor;
• at least one memory device;
• a computer readable storage medium having computer program code that in response to being executed by the processor performs operations, the operations comprising:
• maintaining an active cache list indicating tracks in an active cache comprising a first portion of the at least one memory device to cache the tracks in the storage during computer system operations;
• maintaining an inactive cache list indicating tracks demoted from the active cache;
• during caching operations, gathering information on active cache hits comprising access requests to tracks indicated in the active cache list and inactive cache hits comprising access requests to tracks indicated in the inactive cache list, wherein the gathered information indicates cache hits and cache performance that would be realized if an inactive cache was configured for use with the active cache;
• and
• using the gathered information to determine whether to provision a second portion of the at least one memory device unavailable to cache user data to be part of the active cache for use to cache user data during the computer system operations.

A method for managing a cache provisioned in at least one memory device in a computer system to cache tracks stored in a storage, comprising:

• maintaining an active cache list indicating tracks in an active cache comprising a first portion of the at least one memory device to cache the tracks in the storage during computer system operations;
• maintaining an inactive cache list indicating tracks demoted from the active cache;
• during caching operations, gathering information on active cache hits comprising access requests to tracks indicated in the active cache list and inactive cache hits comprising access requests to tracks indicated in the inactive cache list, wherein the gathered information indicates cache hits and cache performance that would be realized if an inactive cache was configured for use with the active cache;
• and
• using the gathered information to determine whether to provision a second portion of the at least one memory device unavailable to cache user data to be part of the active cache for use to cache user data during the computer system operations.