NETWORK AND I/O CHARACTERISTICS OF ISP MAIL SERVERS

by GAO, HONGYAN

This thesis presents a performance study of the ISP (Internet ServiceProvider) mail servers. By using the SPECmail2001 benchmark to test a commercial mail service – MDaemon mail server, both the network and the I/O performance of mail servers with user populations between 200 and 10,000 were studied. File system traces were collected for analysis. From the benchmark results, trace-driven simulations and offline trace analysis, several important conclusions for the ISP mail servers were made and the technical suggestions were given correspondingly. It is observed that, in SMTP and POP sessions, the initial network connection setup usually takes a very long time comparing to other phases. I/O latencies contribute up to 40 – 55\% of the data transfer time of the e-mail requests, especially when the user population is high. It is also found that mail servers have better file system temporal and spatial locality than web servers. Most files are short-lived. Because of the skewed file access patterns, a reasonably-sized file system cache can capture most file accessed.