An Experimental Study of Memory Fault Latency

The difficulty with the measurement of fault latency is due to the lack of observability of the fault occurrence and error generation instants in a production environment. This paper describes an experiment, using data from a VAX 11/780 under real workload, to accurately study fault latency in the memory subsystem. Fault latency distributions are generated for s-a-0 and s-a-1 permanent fault models. The results show that the mean fault latency of an s-a-0 fault is nearly 5 times that of the s-a-1 fault. An analysis of variance is performed to quantify the relative influence of different workload parameters on the measured latency.