"Clusters of servers running Sendmail can deliver high performance and high availability at competitive prices. For experienced systems administrators, this has long been a commonly held practice. This article describes our study to quantify and describe ways to achieve highly available/scalable sendmail.

We studied several configurations of Sendmail clusters on Linux and quantified their relative performance. We investigated and tested common performance tuning parameters in Sendmail's configuration and in the Linux operating system. We didn't have a shared disk for these tests, so we scoped the project to include SMTP routing and queueing only. This would be a common configuration for a Sendmail cluster on the edge of a private network or as the front-end for an internal mail store.

While our hardware resources were modest, we believe the relative differences make our results valuable to system architects who want to implement clusters of Linux-based Sendmail servers, because our results illustrate the relative importance of a Sendmail cluster's design features."

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