Slow or balky e-mail is guaranteed to generate complaints from your users.
Unfortunately, it's all too easy to experience storage performance bottlenecks with Microsoft Exchange. Exchange stores several different types of information that perform best with different kinds of storage. This makes it difficult to estimate storage requirements, especially storage I/O requirements. Estimates that are off target can result in performance problems.
Jetstress is an Exchange system simulation tool from Microsoft that lets you test your Exchange storage system before you put it into production. You can download Jetstress from Microsoft's Exchange 2003 Web site and use it to test your storage system against your expected load and latency requirements.
Jetstress runs two different tests. The Disk Performance Test verifies storage performance and sizing and gives you the saturation limit of your drive. This will let you check your performance when your system is fully loaded. The second test, the Disk Subsystem Stress Test, puts pressure on your server with a much larger load over a longer period of time to see if your system becomes flaky under heavy loads. The Disk Performance Test takes about two hours to run, and the Disk Subsystem Stress Test runs for 24 hours.
Microsoft emphasizes that you should only use Jetstress in a non-production environment -- you should not run it on a "live" Exchange system.
It is fairly easy to spot performance problems in Microsoft Exchange using the performance logs to keep track of relevant statistics. If Jetstress shows there is a problem, you can usually find the cause readily by studying the logs. The fix may be more complex, since getting the best performance out of Exchange involves things like using different RAID levels for different kinds of data and making sure some files are on separate physical disks.
About the author
Rick Cook has been writing about mass storage since the days when the term meant an 80 KB floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years, Cook has been a freelance writer specializing in storage and other computer issues.
