Hitachi Data Systems Corporation

Milton Wayne Demaray

William Gary Cox

Thomas A Attanese

A disaster recovery technique for computer systems obtains backup copies of data by arranging recording devices like direct-access disk devices into copy pairs of primary and secondary devices. Management of the device copy pairs within a single system and across multiple systems is facilitated by constructing maps of device information that provide a cross-reference between I/O subsystem device numbers and hardware addresses. Information structures are constructed from the maps and used to facilitate defining and managing groups of device copy pairs.

Methods and apparatuses for providing copies of stored data for disaster recovery and other uses

A standardized test environment assists identifying problematic instances of instructions in computer programs that produce erroneous results. A standardized production environment takes corrective action for selected instructions by intercepting instruction processing during instruction fetch, instruction decode or instruction execution and modifying one or more values such that the instructions achieve correct results. In one embodiment of a test environment, a computer system collects diagnostic information for designated instructions such as subtraction operations that produce negative results. In one embodiment of a production environment, a computer system intercepts instruction processing for instructions at specified locations in a program and takes corrective action according to information obtained from a table of control information.

Taking corrective action in computer programs during instruction processing

A standardized test environment assists identifying problematic instances of instructions in computer programs that produce erroneous results caused by dates having years expressed in a truncated form. A standardized production environment takes corrective action for specified instances of instructions by modifying one or more values such that the instructions achieve correct results. In one embodiment of a test environment, a computer system collects diagnostic information for instances of subtraction operations that produce negative results. In one embodiment of a production environment, a computer system intercepts execution of a computer program at specified locations and takes corrective action according to information obtained from a table of control information.

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Fremont, CA, United States of America

Milton Wayne Demaray