Apparatus and method for analyzing and modifying data transfer reguests in a raid system

摘要

The invention provides a method and apparatus for increasing the efficiency of data transfer between a host computer and a disk array in a RAID system. The invention operates by splitting up large I/O requests from the computer into smaller, more manageable pieces and processing the pieces as though they were individual I/O requests. In one embodiment, the invention keeps only a limited number of these smaller individual I/O requests "active" at any particular time so that a single large I/O request cannot preclude other I/O requests from making progress in the controller. Both the size of the smaller I/O request pieces and the limited number of these pieces which will be "active" at any one time may be tunable parameters. The invention improves the efficiency of data transfer between the host computer and the array of disk drives by providing for increased overlap of activity in the controller. This increased overlap of activity results in increased controller throughput.