A Replicated Monitoring Tool

Modeling the reliability of distributed systems requires a good understanding of the reliability of the components. Careful modeling allows highly fault-tolerant distributed applications to be constructed at the least cost. Realistic estimates can be found by measuring the performance of actual systems. An enormous amount of information about system performance can be acquired with no special privileges via the Internet. A distributed monitoring tool called a tattler is described. The system is composed of a group of tattler processes that monitor a set of selected hosts. The tattlers cooperate to provide a fault-tolerant distributed data base of information about the hosts they monitor. They use weak-consistency replication techniques to ensure their own fault-tolerance and the eventual consistency of the data base that they maintain.