Controller communications over an always-on controller interconnect

Abstract

A controller interconnect structure within a RAID disk array enables continuous low latency/high bandwidth communications between a plurality of controller pairs within the array. Mirror buses carry high speed mirror traffic between mirrored controllers performing mirrored memory operations. Loop buses carry inter-processor communications and other traffic between controller pairs coupled together in a controller loop. Benefits of the interconnect structure include an ability to support continued controller communications and online disk array operations under various failure and repair conditions that might otherwise render a disk array inoperable. In addition, the controller interconnect structure provides for easy expansion of the number of controllers within disk arrays as arrays continue to be scaled up in size to meet increasing storage demands from user host systems.