Data storage system with asynchronous host operating system

Abstract

This invention provides disk drive access control apparatus for connection between a host computer and a plurality of disk drives to provide an asynchronously operating storage system. It also provides increases in performance over earlier versions thereof. There are a plurality of disk drive controller channels connected to respective ones of the disk drives and controlling transfers of data to and from the disk drives, each of the disk drive controller channels includes a cache/buffer memory and a micro-processor unit. An interface and driver unit interfaces with the host computer and there is a central cache memory. Cache memory control logic controls transfers of data from the cache/buffer memory of the plurality of disk drive controller channels to the cache memory and from the cache memory to the cache/buffer memory of the plurality of disk drive controller channels and from the cache memory to the host computer through the interface and driver unit. A central processing unit manages the use of the cache memory by requesting data transfers only of data not presently in the cache memory and by sending high level commands to the disk drive controller channels. A first (data) bus interconnects the plurality of disk drive cache/buffer memories, the interface and driver unit, and the cache memory for the transfer of information therebetween and a second (information and commands) bus interconnects the same elements with the central processing unit for the transfer of control and information therebetween.