Reliability analysis of simplex and duplex memory systems with SEC and soft-error scrubbing recovery

Reliability of RAM memory systems is impaired by environmental disturbances, causing soft errors, whereby one data bit is transformed to another bit. Single-error correcting codes with memory scrubbing offer the most effective method to recover from such errors. This paper analyzes the reliability and determines the MTTF for simplex and duplex memory systems with single-error correction and or soft-error scrubbing recovery. It extends previous work on the deterministic scrubbing recovery of simplex memory systems by using a more general model that takes into account cancelling soft errors. In the duplex memory system an additional level of static redundancy is proposed by employing a decoding algorithm at the memory module level. The reliability analysis of the duplex system with soft-error scrubbing takes into account the decoder output which upon scrubbing transforms words with a number of multiple errors to words with a different number of errors. Computer results show that this combination of data and system redundancy provides more reliability than either data or system redundancy alone.