System for using mirrored memory as a robust communication path between dual disk storage controllers

摘要

In a disk storage system having dual controllers and mirrored memory therebetween, the mirrored memory is used to establish a robust communication path between the controllers to monitor and coordinate their activities. A reserved portion of the memory in each controller is designated as a messaging mailbox which is read and written by the owning controller but only read by the remote controller. The communication protocol between the controllers is tightly coupled to insure proper messaging. Furthermore, a sliding window interlock insures message detection and correctness. In addition, interrupt signals and timer based polling are used as a dual means for detecting communication requests and replies between the controllers.