This Article 
 Bibliographic References 
 Add to: 
Comparison of Duplex and Triplex Memory Reliability
April 1996 (vol. 45 no. 4)
pp. 503-507

Abstract—A large number of choices exist when designing a reliable memory system. The choices range from simple replication to complex error control codes (ECC). An intermediate solution is to use combination of replication and simple ECC. Such a system consists of multiple memory modules, data stored in each module being encoded using an ECC. This paper compares reliability of memory systems formed using simple triplication (without ECC) with memory systems formed by duplicating memory modules that use ECC. It is shown that reliability achieved by duplication of memory modules using codes capable of only error detection or only single error correction (SEC), is always worse than simple triplication. However, it is also shown that duplication of memory modules, with codes capable of single error correction and double error detection (SEC-DED), can achieve better reliability than simple triplication when bit error probability is small.

[1] P.A. Bernstein,"Sequoia: A Fault-Tolerant Tightly Coupled Multiprocessor for Transaction Processing," Computer, pp. 37-45, Feb. 1988.
[2] W.E. Boyce and R.C. DiPrima,Calculus. John Wiley&Sons, 1988.
[3] B.W. Johnson, Design and Analysis of Fault-Tolerant Digital Systems, pp. 394-402. Reading, Mass.: Addison-Wesley, June 1989.
[4] T.R.N. Rao and Fujiwara, Error-Coding for Computer Systems.Englewood Cliffs, N.J.: Prentice Hall, 1989.
[5] D.P. Siewiorek,"Reliability Modeling of Compensating Module Failures in Majority Voted Redundancy," IEEE Trans. Computers, vol. 24, pp. 525-533, May 1975.
[6] N.H. Vaidya,"Duplex and Triplex Memory: Which is more Reliable?" Tech. Report 94-025, Computer Science Dept., Texas A&M Univ., College Station, Feb. 1994.
[7] N.H. Vaidya and D.K. Pradhan, “Fault-Tolerant Design Strategies for Reliability and Safety,” IEEE Trans. Computers, vol. 42, no. 10, pp. 1,195-1,206, Oct. 1993.

Index Terms:
Reliability, replication, coding, modular redundancy.
Nitin H. Vaidya, "Comparison of Duplex and Triplex Memory Reliability," IEEE Transactions on Computers, vol. 45, no. 4, pp. 503-507, April 1996, doi:10.1109/12.494111
Usage of this product signifies your acceptance of the Terms of Use.