External I/O controller system for an independent access parity disk array

摘要

An external I/O controller system between a host system and a Redundant Array of Independent Disks (RAID) array, having a processor complex for coordinating RAID parity write operations to a member disk in a RAID array, and a cache memory complex that asynchronously executes the RAID parity write operation independent of the processor complex and any processor complex resources. The cache memory complex includes a first cache memory and a second cache memory that operate in concert to achieve increased RAID parity write efficiency for a RAID Level 3, 4, 5, or 6 write operation. The I/O controller of the present invention also performs substantially concurrent manipulations on the new host data being written to the RAID array and the old host data and old parity data used to generate a new parity data corresponding to the new host data.