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This paper describes a fully redundant clock generation and distribution approach with a fully dynamic switchover capability and concurrent repair. It highlights the challenges as the design evolved from a single source, to a “cold” standby backup, and finally to a fully redundant transparent switchover with no interruption of the workloads running on an IBM System z9™. The function split between hardware and the various levels of firmware is described, including the methods to determine the defect component in the clock distribution paths. Finally, we describe the joint effort with a major chip technology vendor to design and develop the necessary circuitry, according to the z9™ requirements, for clock synchronization and switching.
Note: The Institute of Electrical and Electronics Engineers, Incorporated is distributing this Article with permission of the International Business Machines Corporation (IBM) who is the exclusive owner. The recipient of this Article may not assign, sublicense, lease, rent or otherwise transfer, reproduce, prepare derivative works, publicly display or perform, or distribute the Article.
Date of Publication: Jan. 2007