[R] System Reliability Metrics

From: Jon Stearley <jrstear_at_sandia.gov>
Date: Thu 22 Dec 2005 - 05:02:34 EST

I need to calculate some metrics such as Mean Time Between Failure
(MTBF), etc (see http://www.cs.sandia.gov/~jrstear/ras for a more
complete list). I have observations like

                  start                 end                state
  1 2005-11-11 09:05:00 2005-11-11 12:20:00 Scheduled Downtime   2 2005-11-12 13:42:00 2005-11-12 14:45:00 Unscheduled Downtime

where each row describes the system state between start and end times. Time between observations indicates a Production state. The metrics of interest involve simple ratios of total time spent in various states, number of transitions, etc. I'd like to plot period MTBF values (eg monthly vertical bars), as well as a cumulative MTBF
(eg a line whose last value indicates MTBF for the entire time
range), etc.

What is the best approach in R towards these results?

Irregular time series seem a natural fit for the observations, and the reporting periods for the metrics will have regular periods - so I've perused the stats, tseries, and its packages. A markov class could be used (eg msm package), but that's probably overkill (like the reliability packages concord and irr)? My goal is to calculate the metrics in the simplest and most natural way. Can someone please advise me on a best approach?

Thank you!

| Jon Stearley                  (505) 845-7571  (FAX 844-9297) |
| Sandia National Laboratories  Scalable Systems Integration   |

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Received on Thu Dec 22 05:08:33 2005

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