Patent ID: 7043663

Claim:
A storage area network comprising: a plurality of loosely-coupled storage controllers arranged in a redundant configuration to provide, to a plurality of servers, access to virtualized storage, wherein one of the storage controllers operates as a master storage controller and the other storage controller or controllers operate as slave storage controllers; a respective monitoring application executing on each of the storage controllers configured to determine whether or not the storage controllers are operating properly; and two or more communication channels coupling the storage controllers and wherein: the storage controllers are logically arranged in a binary tree having a root node and one or more child nodes such that the master storage controller is the root node of the tree and the slave storage controller or controllers are the child nodes, wherein the root node and each child node have, at most, two associated child nodes; and each particular node is configured to periodically send, over at least one of the two or more communications channels, a respective inquiry message to each of its associated child nodes and, in response to an inquiry message, each associated child node is configured to send, over at least one of the two or more communications channels, an acknowledgement message to its parent node.