A practical dependability measure for degradable computer systems with non-exponential degradation
Artikel i vetenskaplig tidskrift, 1994
This paper proposes a vectorized measure for a set of behavioural dependability attributes. The measure is based on Markov processes and is intended for practical dependability trade-offs. It describes the system performance on a number of service levels. Thus, it is possible to merge attributes such as reliability, safety and
performability into one single quality. Whereas reliability describes the functional fulfillment of a system, performability reflects its ability of functional degradation. The safety attribute handles a class of failures with catastrophic consequences and can be
accommodated by means of introducing two or more service levels for a failed system.Many systems exhibit time-dependent degradation rates and non–exponential
lifetimes. This situation can be handled by means of applying phase–type assumptions and introducing some additional states to the system, which would allow us to
remain within the universe of Markov modelling.