Abstract: In a computer system having a plurality of electronic subsystems therein adapted to receive main electrical power from an interruptible main power supply, ones of the electronic subsystems being designated as critical to retention of user data in the computer system in an event of interruption of the electrical power from the main power supply, a backup power subsystem and method for controllably delivering backup electrical power to the ones of the electronic subsystems. The subsystem comprises: (1) a central electrical power storage cell having a particular capacity and adapted to be maintained in a constantly charged state, (2) a backup electrical power bus coupled to the central electrical power storage cell and adapted to be selectively coupled to selected ones of the electronic subsystems and (3) a backup power management controller adapted to couple the backup electrical power bus to the selected ones of the electronic subsystems.

Abstract: A method and system for providing fault tolerance in a networked client/server computing environment by introducing a server computer comprised of a first computer with a first secondary storage controller and a first communications controller and a second computer with a second secondary storage controller and a secondary communications controller. The invention introduces a high speed communications channel that runs between secondary storage controllers and communications controllers in each of the computers, thereby allowing data flow between the communications controllers and enabling the first and second computers to mirror each other or cooperate to form a cluster server. In addition, the communications channel serves as a pathway for secondary storage I/O dataflow, thereby enabling the first and second computers to share secondary storage resources.