Measurement-based availability analysis of Unix systems in a distributed environment

This paper presents a measurement-based availability study of networked Unix systems, based on data collected during 11 months from 298 workstations and servers interconnected through a local area computing network. The data corresponds to event logs recorded by the Unix operating system via the Syslogd daemon. Our study focuses on the identification of machine reboots and the evaluation of statistical measures characterizing: (a) the distribution of reboots (per machine, time), (b) the distribution of uptimes and downtimes associated to these reboots, (c) the availability of machines including workstations and servers, and (d) error dependencies between clients and servers.