Performance Testing a SAN

By Andrew Garcia  |  Posted 2002-05-15 Print this article Print

The best benchmarks are always the ones you run yourself using your own application to generate load. When it is not practical to benchmark this way, the next best alternative is to use a widely used benchmark suite that is accepted both by the vendor and user communities. In the world of storage, Intels older Iometer tool is the most well known storage system benchmark around. Iometer is freely downloadable from Intels Web site, and since many vendors publish numbers using this benchmark, its possible to get some comparative data between different storage systems. For the most part, Iometer is very easy to use and since it doesnt require a large test bed to set up, it is a good tool to have around the lab.
Although Iometer doesnt use real application data to create its load, using the benchmark controls its easy to create test mixes to simulate your application needs.
Iometer Using Iometer you should create a test suite that behaves similar to your applications. For example if you are trying to support a streaming media application, you should configure a test suite where most requests are sequentially reading data from a storage system. Iometer has the ability to approximate both the percentage of read and write transactions and the percentage of random to sequential requests. In most cases, to max out the throughput of a SAN storage system (to stress the storage devices and the network components together), we typically run a sequential read test with a large request size (around 1 MB). Unfortunately, there are very few applications in which a large sequential read is the only type of transaction required. Usually when vendors publish performance numbers on their subsystems, the large request sequential read test is the number they publish, but buyers should be careful to check the testing disclosure of a vendor test before accepting their numbers at face value. Included with Iometer are sample test suites to simulate database server, streaming media, webserver, and file server traffic. These suites are a good baseline tests to run before formulating your own suites. Now if only Intel would keep updating the test to keep up with improvements in storage technologies. Conclusion
While SAN implementation is still not an easy task, key tasks like storage centralization and disaster recovery can be greatly enhanced through the use of Fibre Channel SANs. Although we may be a few years away from having plug and play SANs such as those we might want to use in our homes in addition to our businesses, in many cases the inconveniences created by being on the cutting technology are far less than the rewards of implementation.

Andrew cut his teeth as a systems administrator at the University of California, learning the ins and outs of server migration, Windows desktop management, Unix and Novell administration. After a tour of duty as a team leader for PC Magazine's Labs, Andrew turned to system integration - providing network, server, and desktop consulting services for small businesses throughout the Bay Area. With eWEEK Labs since 2003, Andrew concentrates on wireless networking technologies while moonlighting with Microsoft Windows, mobile devices and management, and unified communications. He produces product reviews, technology analysis and opinion pieces for, eWEEK magazine, and the Labs' Release Notes blog. Follow Andrew on Twitter at andrewrgarcia, or reach him by email at

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