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utwente-fmt / dftcalc

DFTCalc: A Dynamic Fault Tree calculator for reliability and availability
http://fmt.ewi.utwente.nl/tools/dftcalc/
MIT License
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BE attribute "res" is ignored (feature request: implement it!) #6

Open hobborg opened 5 years ago

hobborg commented 5 years ago

The description of the res attribute for BEs as found in this page doesn't seem to be implemented.

To see that, run the tool with options -p -s -m on the following FT, and then again on that FT but replacing res=1.0 by res=0.0. The expected behaviour is that for run with res=0.0 the MTTF remains the same but the unavailability increases: that is not happening and for both cases the exact same results are given.

toplevel "TLE";
"TLE" and "B1" "B2";
"B1" lambda=0.09 res=1.0 repair=1.3;
"B2" lambda=0.12 res=1.0 repair=1.3;

Furthermore, res should be a probability value in the closed interval [0.0,1.0]. However any value is currently accepted (and seemingly ignored) by the tool. To reproduce run with the options as above on the same FT with res=80085.

ennoruijters commented 5 years ago

The res attribute has been added, however it does not do what you expect: Following the Galileo manual (https://www.cse.msu.edu/~cse870/Materials/FaultTolerant/manual-galileo.htm), a failure should, with res probability, not "cause the failure of either the component or the system". This has been implemented as an immediate repair of the component without any intervening failure. I intend to add a new attribute (e.g., transient) to perform the behaviour you describe, but this will take some time as the introduction of zero-time failure states has implication for most of the automata and the resulting CTMCs and queries.