Sequential cache management system utilizing the establishment of a microcache and managing the contents of such according to a threshold comparison

A data storage system comprising:

• a plurality of host computers and a plurality of data storage devices,
• a system memory coupled to said host computers and said storage devices for storing data elements provided by said host computers, said system memory comprising;
• a cache memory for storing data elements from either the host computers or the data storage devices,
• a replacement queue within said memory for ordering information stored in said cache memory,
• said replacement queue further including a microcache for responding to sequential operations, and
• a cache manager for sensing a sequential operation and for establishing a microcache when a sequential operation occurs,
• said cache manager sensing when said replacement queue is stressed and servicing said sequential operations from said microcache when said replacement queue is stressed.