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Conclusions

Maelstrom is a relatively simple tool. But it is a result of complex and perhaps controversial changes in our thinking about the troubleshooting process. What we want is not necessarily what we need. It would be nice if we could predefine the script that accomplishes troubleshooting, by implementing a decision tree as a script. This does not work. It would be nice if we could predefine precedences between troubleshooting tasks. We cannot. It would be nice if the result of scripting was a description of the problem that was solved. As we often do not know the causes of problems when solving them as human troubleshooters, this is an idle dream.

The lesson of Maelstrom is that there are things we can do to automate troubleshooting without running into these roadblocks. We can employ convergence as a replacement for causal theory. We can concentrate on effects, and base the modularity of our automation upon consistency and agreement upon the effects we wish to achieve, and reliable reporting of effects, rather than agreement upon software interfaces or platforms. We can compensate for lack of agreement by sequencing.

But taking these steps also requires casting aside some commonly held values. We must remember that machine labor is cheap while staff labor is expensive, so that an inefficient machine process is sometimes preferable to an efficient one performed by a human. In utilizing machine labor, however, it is important to keep the automated process understandable and repeatable by a human, so that it can be verified, validated, and improved. Maelstrom does not use the most efficient strategy, but the most understandable one.

Research is itself a convergent process, so it is not surprising that many others have faced the same problems in other areas and come to some of the same conclusions. The need to limit ourselves to cases that are observable is echoed in current work on testing of distributed software systems[6,11]. Safety (freedom from undesirable states) and liveness (freedom from deadlocks) are goals of both software engineering and system administration. Safety and liveness are difficult to assure, even when one has a complete model of what proper operation should be - something a network administrator often lacks.

It is often claimed that learning to be a painter is not so much learning to paint as it is learning to see. Here we have the same effect; we need to learn to trust our senses rather than our theories, our results more than our models. Only then can we sort out the maelstrom that is troubleshooting, and can truly know that we can ``paint what we see.''


next up previous
Next: Availability Up: No Title Previous: Limitations
Alva L. Couch
2001-10-02