Title :
The IBM S/390 Sysplex Timer
Author :
Smith, T.B. ; Moorman, W.A. ; Dang, T.
Abstract :
The IBM S/390 Sysplex Timer, a centralized fault-tolerant time reference used in maintaining time-of-day synchronism between multiple closely coupled IBM S/390´s, is presented. The basic Sysplex Timer organization is quad redundant, and its packaging is duplex. A fully duplicated star interconnect topology provides redundant timer transmissions to every S/390 client system using dedicated fiber optic cables. The technology used in the design of the Sysplex Timer and measurements of the performance of the prototype system used in the validation of the design are presented. The design proved to be economic and robust, maintaining tightly synchronized operation of the redundant components for all test cases. Cable latency compensation appeared to be particularly effective. Worst case operation of the prototype with less than 300 ns of timer skew was verified.<>
Keywords :
clocks; computer architecture; fault tolerant computing; timing circuits; IBM S/390 Sysplex Timer; cable latency compensation; centralized fault-tolerant time reference; dedicated fiber optic cables; fully duplicated star interconnect topology; quad redundant; tightly synchronized operation; time-of-day synchronism; worst case operation; Couplings; Delay; Fault tolerance; Optical fiber cables; Optical fibers; Packaging; Prototypes; Robustness; Testing; Topology;
Conference_Titel :
Fault-Tolerant Computing, 1991. FTCS-21. Digest of Papers., Twenty-First International Symposium
Conference_Location :
Montreal, Quebec, Canada
Print_ISBN :
0-8186-2150-8
DOI :
10.1109/FTCS.1991.146653
