International Business Machines Corporation

John R Wolfe

Brent Cameron Beardsley

Cortland D Starrett

Michael T Benhase

James Lincoln Iskiyan

David L Leigh

A data processing system regulating access from a plurality of host computers to a plurality of direct access storage devices. The data processing system has a storage controller connected for data communication to the host computers by one or more channels per host computer. The storage controller is further connected to direct access storage devices used to provide auxiliary storage. The storage controller, responsive to host computer request, selectively establishes a communication link for data transfer between the host computers and the direct access storage devices. Channels are temporarily disqualified from obtaining control of the storage controller or a storage device during periods of contention for access to the storage devices or the storage controller. Transmission of device end and control unit end signals is also selective by channel. Override conditions are specified to allow for host computer or channel failure without disabling the data processing system.

System and method for regulating access to direct access storage devices

A method and system in a data processing system for the efficient response to multiple different types of interrupts. The data processing system includes at least one host and a storage subsystem having storage subsystem devices and at least one storage subsystem controller. The storage subsystem controller operates in multiple different states. Interrupts of multiple different types are generated by sources of real time events and are received by the storage subsystem controller. A selected type of interrupt as a preferred next interrupt to be received by the storage subsystem controller is then determined in response to the determination of the current state of the storage subsystem controller. A particular state associated with the occurrence of the selected type of interrupt is then determined. Reversible processing associated with the particular state is initiated prior to receipt of a next interrupt wherein the selected type of interrupt is efficiently enhanced in priority in response to the current state of the storage subsystem controller.

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Tucson, AZ, United States of America

John R Wolfe