Modeling Correlation in Software Recovery Blocks

This paper considers the problem of accurately modeling the software fault-tolerance technique based on recovery blocks. Models of such systems have been criticized for their assumptions of independence. Analysis of some systems have considered the correlation between software modules. This correlation may be due to a portion of the functional specification that is common to all software modules or due to the inherent hardness of some problems. We consider three types of dependence which can be captured using measurements. We consider correlation between software modules for a single input, correlation between successive acceptance tests on correct module outputs and incorrect module outputs, and correlation between subsequent inputs. The technique we use is quite general and can be applied to other types of correlation. In accounting for dependence, we use the intensity distribution introduced by Eckhardt and Lee. We consider a new method of generating the intensity distribution which is based on the pairwise correlation between modules. This method provides us with a pessimistic result and a probability-based approximation. We contrast this method with the assumption of independent modules as well as the use of the beta-binomial density which was introduced by Nicola and Goyal. For the purpose of obtaining numerical results, we use stochastic reward nets (SRN's) that incorporate all of the above dependencies and then use a modeling tool called Stochastic Petri Net Package (SPNP). © 1993 IEEE

Duke Scholars

Author Kishor S. Trivedi Electrical and Computer Engineering