Adaptive Fetch Policy Mechanism
Original Publication Date: 1980-Apr-01
Included in the Prior Art Database: 2005-Feb-13
This article describes a method for miss ratio management in a storage subsystem including a control unit attaching a DASD (direct access storage device) backed cache, a DASD, and one or more channels. Demanded records both referenced by the channel and absent on the cache are selectively staged. The method steps comprise: (1) upstaging a track inclusive of the missed record to the cache based on a probability function; (2) monitoring the miss ratio and miss rate over consecutive intervals; and (3) modifying the probability function for upstaging a track based on the behavior of the miss ratio and miss rate over past consecutive intervals.