Recovery modeling in performability analysis for multi-computer systems
Performability is an attribute of a system which combines reliability and performance. Recovery procedures in gracefully-degradable multi-computer systems can have significant influence on performability. A methodology is proposed in this paper to incorporate recovery modeling into performability analysis. This allows the derivation of probabilities for each performance level under different recovery schemes. A general model for n-primary, m-spare multi-computer systems is developed. Also, a general model for pair and spare multi-computer systems is formed in the paper. Several examples are given to demonstrate the methodology. These examples show that the methodology provides more accurate information about the performability of the system being investigated. The use of this methodology, when combined with existing performance evaluation techniques, can help system designers to obtain an accurate evaluation of the performability of systems with recovery and to compare the effect of varying recovery procedures.