The Effect of Correlated Failure Rates on Reliability of Continuous Time 1-Out-of-2 Software

  • Peter Popov
  • Gabriele Manno
Part of the Lecture Notes in Computer Science book series (LNCS, volume 6894)


In this paper we study the effects on system reliability of the correlation over input space partitions between the rates of failure of two-channel fault-tolerant control software. We use a continuous-time semi-Markov model to describe the behavior of the system. We demonstrate via simulation that the variation of the failure rates of the channels over the partitions of the input space can affect system reliability very significantly. With a plausible range of model parameters we observed that the mean time to system failure may vary by more than an order of magnitude: positive correlation between the channel rates makes the system less reliable while negative correlation between the channel rates implies that the system is more reliable than assuming constant failure rates for the channels. Our observations seem to make a case for more detailed reliability measurements than is typically undertaken in practice.


Hazard Rate System Reliability Sojourn Time System Failure Software Reliability 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Peter Popov
    • 1
  • Gabriele Manno
    • 2
  1. 1.Centre for Software ReliabilityCity UniversityLondonUK
  2. 2.Department of Mathematics and InformaticsUniversity of CataniaCataniaItaly

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