System and method to monitor and isolate faults in a storage area network

Abstract

A fiber channel storage area network (SAN) provides virtualized storage space for a number of servers to a number of virtual disks implemented on various virtual redundant array of inexpensive disks (RAID) devices striped across a plurality of physical disk drives. The SAN includes plural controllers and communication paths to allow for fail-safe and fail-over operation. The plural controllers can be loosely-coupled to provide n-way redundancy and have more than one independent channel for communicating with one another. In the event of a failure involving a controller or controller interface, the virtual disks that are accessed via the affected interfaces are re-mapped to another interface in order to continue to provide high data availability. In particular, deadman timers, heartbeat signals internal to each controller, and heartbeat signals between different controllers are used to detect controllers that are no longer communicating with other controllers in order to identify those controllers which are failing or have failed.