Fail-over control in a computer system having redundant service processors

Abstract

A system and method for determining an active service processor from two or more redundant service processors in the system. The system typically includes two management modules and at least one managed subsystem such as a server blade. Each management module includes a service processor and control logic. The control logic is configured to receive various status signals from the service processor and to generate a control signal based thereon. The control signal is provided, via an interconnect plane, to determination logic on each managed subsystem. The determination logic receives a control signal from each management module and generates a switch signal based on the state of the control signals. The switch signal controls switching logic configured to receive bus signals from the service processors on each management module. Based on the control signal, one of the service processor bus signals is provided to managed instrumentation on the managed subsystem. The management module control logic is generally configured to maintain the control signal in its current state if the active processor is determined to be functional. The control logic is further configured to alter the control signal state if the active service processor is determined to be non-functional. A transition in the control signal typically generates a fail-over event that causes the switching logic on the managed subsystems to switch from the previously active service processor to the previously inactive or standby service processor as the source of service processor signals.