Three hardware don'ts when optimizing Exchange Server performance

If you want to optimize Microsoft Exchange Server performance, start at the server hardware level. What is the best hardware setup for Microsoft Exchange? How much memory do your Exchange servers require? Should you trust your hardware vendor? There are plenty of Exchange Server performance tips and best practices, but here are three things you should never do in order to keep your Exchange servers running in peak condition.

There are many tips and best practices you can follow to improve Microsoft Exchange Server's performance. But here are three things you should never do at the hardware level if you want to optimize Exchange Server performance.

1. Don't use a single-core processor on an Exchange mailbox server.

When it comes to Exchange system performance, using a single-core CPU on a mailbox server is one of the biggest mistakes you can make. The actual impact of doing so, however, varies depending on which version of Microsoft Exchange Server you're running and on how many mailboxes the server is hosting.

More on Exchange Server performance and hardware:

  • Optimizing Exchange Server disk performance
  • Solve server problems with the Exchange Troubleshooting Assistant tool
  • Improve Exchange 2003 Internet connectivity, mail flow and performance
  • Exchange Server Standard Maintenance Checklist
  • How to spec your Exchange server hardware requirements

For several years, I ran Exchange Server 2003 Enterprise Edition on a single core, 32-bit Pentium III with 1 GB of RAM. The Exchange server performed well, but it only hosted five mailboxes.

Exchange Server 2007 is far more demanding than Exchange 2003. When Exchange 2007 was first released, I wanted to add several new Exchange servers to my lab environment. Unfortunately, I tried to keep costs down by purchasing a few 64-bit servers with 2 GB of RAM and a single-core AMD processor.

Although the Exchange mailbox server wasn't hosting any production mailboxes, it ran painfully slow. Merely clicking on a container in the Exchange Management Console (EMC) would cause a 20-second delay before the screen would refresh. Eventually, I replaced this server with one that had a quad-core processor; the difference was noticeable.

What does Microsoft have to say about CPU cores and their affect on Exchange Server? According to the Microsoft knowledgebase article, CPU and memory scalability for Exchange Server 2003 and for Exchange 2000 Server, a dual-core processor's performance can be up to 90% better than what a comparable single-core CPU can deliver on servers running Exchange 2000 or 2003. In addition, Exchange 2000 and 2003 servers can take full advantage of up to eight CPUs (or CPU cores).

2. Don't assume that the hardware vendor is telling the truth.

It's tempting to assume that hardware vendors know what they're talking about. But for the sake of Exchange Server performance, don't. Recently, I needed to purchase a new server. Because of the last-minute nature of the project, I didn't get a chance to research available servers.

For this particular deployment, I needed an Exchange server with a quad-core processor and a bare minimum of 8 GB of RAM for performance. I found a server at a reasonable price that looked like it might get the job done, but it only came with 2 GB of RAM. The salesperson said the memory could be expanded to 16 GB. That was perfect for my needs, but I decided to double check.

After searching the Internet, I discovered that the server in question was only expandable to 4 GB. The salesperson had fed me a line in an effort to make an easy sale. The point is, even if you've been using the same hardware vendor for a while, it pays to do your homework before you purchase expensive server hardware.

3. Don't assume that adding more memory will increase Exchange Server performance.

A mailbox server with too much memory can hurt Exchange Server performance. The more memory an Exchange 2007 mailbox server has, the longer it takes the server to populate its cache after a reboot. Until a cache has reached its optimal size, the server generally doesn't perform very well.

There are other ways that having too much memory can negatively affect Exchange Server performance. At the hardware level, some servers perform more slowly as memory is increased.

If you use PC3200 memory, hardware limitations will prevent you from installing more than 16 GB of memory on that Exchange server. However, many system boards are backward compatible with less efficient types of memory.

For example, PC2700 memory is slower than PC3200, but it can be used to reach configurations of up to 32 GB (assuming the system board supports this much memory). Theoretically, increasing a server's memory could require using slower hardware.

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Brien M. PoseyABOUT THE AUTHOR:  Brien M. Posey, MCSE, is a five-time recipient of Microsoft's Most Valuable Professional award for his work with Exchange Server, Windows Server, Internet Information Services (IIS) and File Systems and Storage. He has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. As a freelance technical writer, Brien has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies. You can visit Brien's personal website at

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