We need to migrate to a new server and are looking for some hardware guidelines for the new server.
The server will need to support up to 250 users and replicate to 4 sites around the world. Can you give me some guidelines for the number of processors, amount of RAM, and disk space for the Information store and logs?
Ah, that's an age-old question indeedand a surprisingly tough one to answer. It depends a lot upon how active your users are going to be, what limits (if any) you plan to set, how extensively you intend to use public folders, if you plan to do any scripting or automatic routing, and so forth.
Here is my recommended minimum configuration for an Exchange server these days:
- Get a Pentium III-500, two 1GB mirrored drives for the operating system and programs, two 2GB mirrored drives for the transaction logs, and a RAID 5 set (size determined by your usage) for the Information stores. I would start at 128MB RAM but, frankly, 256MB is preferable. Naturally I'd prefer that the server be dedicated to running Exchangenot hosting SQL and other apps too.
- Make sure that the box is easily expandable. You should be able to go to at least four CPUs if you need to, have room for extra hard drives in case your RAID 5 array needs to be expanded, and be able to upgrade the RAM as easily and inexpensively as possible. Those are all things to consider when you select your hardware.
- Don't overlook your network hardware either. Depending on your LAN topology and anticipated load, you should consider multiple 100Mbit NICs or at least a fast switch to connect to the Exchange server.
This configuration will probably run what you need it to, but how fast it will be I cannot say unless I can see it under actual (or at least simulated) load conditions. Optimally you should get the server you decide upon, install it in a lab environment, and then run LOADSIM (the load simulator) against it to see how it holds up under your projected load.
If you don't have that luxury, then you might try starting with a configuration similar to the one I described above, with the understanding that you're going to monitor it closely and possibly make upgrades to the hardware to accommodate whatever performance issues you discover.
Obviously it's really not optimal to test something like that in a production environment, but business issues being what they are I realize that we don't all have the luxury of a test lab to try these things out in first.
The question "How much hardware do I need?" is a common one and unfortunately there aren't any cut and dried answers. The hardware that supports my users might not support yours and vice versa.