Logic for the Placement of Data in a Cache Memory
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
There is disclosed a method for demand accessing DASD (Direct Access Storage Device) data through an LRU (Least Recently Used) cache. If there exists either a cache hit, or if the access density exceeds that of the DASD, then data is staged to the cache. Otherwise, DASD data is staged to main memory. Access density is defined to be the number of accesses per unit time per data volume. Because of the existence of data sets that require an access rate that is higher than a DASD can sustain, a cache memory having a much higher access rate is provided. Data is moved from the DASD to the cache, and from the cache to main memory of the computer for processing. The success of this technique depends on the need for many accesses to the data in the cache for a single access to the DASD.