Software Voting in Asynchronous NMR (N-Modular Redundancy) Computer Structures.

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Abstract:

This paper has explored some of the attributes of NMR computer systems. Many features of software voters have been explored both experimentally and theoretically. Section 2 has presented some software voting concepts. N-modular redundancy has been described and the software concepts of time skew and space redundancy have been explained. Various synchronization issues have been presented, including time-outs, points of synchronization, and asynchronous versus synchronous systems. The frequency of voting and the data granularity were shown to be important factors in determining the reliability of NMR systems. Finally, a technique was described to allow easy bit-by-bit voting on words of data. In Section 4, some experiments were presented to help measure the overhead involved in software voting. The type of voter, the voting frequency, and the average instruction execution time were incorporated into a model of voting overhead. Section 5 shows a number of synchronization experiments. The amount of variation in process execution speed that can be tolerated was determined for three different types of variation.

Author(s):
York, Gary ; Siewiorek, Daniel ; Segall, Zary
Author Organization(s):
CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF COMPUTER SCIENCE
Descriptive Note:
Interim rept.,
Supplementary Note:
Sponsored in part by Contract NASA-NAG-1-190.
Pagination:
0036

Security Markings

DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
CMU-CS-83-128
Contract/Grant Number(s):
DASG60-80-C-0057, NSF-ECS81-20270
 Subject Terms
Joint Capability Areas:
JCA_1.2.7_Experimentation; JCA_5_Command and Control; JCA_1_Force Support; JCA_1.2_Force Preparation; JCA_5.5.2_Task; JCA_5.5_Direct; JCA_1.2.6_Concepts; JCA_6.1.3_Switching and Routing; JCA_6.1_Information Transport; JCA_6_Net Centric; JCA_1.2.5_Lessons Learned; JCA_1.2.3_Educating; JCA_3.2_Engagement; JCA_3_Force Application; JCA_3.2.1_Kinetic Means; JCA_5.3_Planning; JCA_1.3_Human Capital Management; JCA_5.4_Decide
Modernization Areas:
Microelectronics
Communities of Interest:
Materials and Manufacturing Processes
Descriptor(s):
*Computer program reliability, *Computers, *Redundant components, *Modular construction, Computer programs, Computer architecture, Systems engineering, Redundancy, Output, Throughput, Performance(Engineering), Memory devices, Data processing, Failure, Masking, Synchronism, Experimental data, Queueing theory, Models, Algorithms
Field(s)/Group(s):
Theoretical Mathematics, Computer Programming and Software, Computer Hardware
Keyword(s):
Software voting, NMR(N Modular Redundancy), TMR(Triple Modular Redundancy)
Report Date:
1983 May 06