Server for Exchange Server

Your first concern should be disk I/O.

Are Blackberries or Windows Mobile devices in the picture? Factor about a 3.4 times factor on disk I/O for those.

Your OS and transaction files should be on a set of mirrored drives.

Your database should be on Raid 5 or a SAN if you can afford it.

You can figure you current disk I/O by looking at the performance counter in Physical Disk/Disk Transfers per second.

Also be sure to look at Physical Disk/% Idle time. Subtract the Idle time number from 100 to see the percentage of disk IO available.

You will also want to look at the MSEXCHANGEIS\RPC Operations Per Second counter to get an idea of how hard your clients are hitting the Exchange server.

And don't forget on a clustered solution that you cannot connect more than 1900 MAPI sessions to an Active-Active Cluster. Thus, be sure that you have 3 servers in the cluster operating as an Active/Active/Passive Cluster.

Also be sure to use Load Balanced network cards for maximum redundancy and throughput.

Besides BFF's very good advice I would also say add as much RAM as you can afford and then some more with that many users it's going to help with Disc Transfers and make the system appear faster than it really is.

As BFF said RAID 5 and I would have the OS and Data Files on the RAID Array as if one drive fails with the OS on it you not be out of Acton while an image or reinstall is performed all you need do is replace the dead drive and rebuild it when you have some free time. That's if your RAID controller will support running on 1 Drive instead of 2 for the array. But even if it does that really only safely gives you to the end of business that day to replace the dead drive and perform the rebuild.

You could look at a Dual Core for a CPU but Personally I prefer Dual CPU's as the systems just work better but that my personal experience and you may not have the budget for hardware this expensive.

As this is going to be a [b]Mission Critical Server[/b] don't even think of anything but Intel CPU/s and Chip Set M'Board you can not afford the down time that will happen with anything else.

Col

BFilmfan and Hal all have great suggestions.

when you mention redundancy my first thoughts were as Bfilm mentions, cluster but you could opt for a front end/back end solution [requires more than one exchange but not in a cluster] where users still have intra email and the inter email will stay in the transport queue should the front end server take a dive.

Your disaster recover backup and restore solution should determine your server configuration. If the server dies, how long will it take you to restore the server after the disaster. Seperate drives may cause headaches in restore from disaster.

Check out this site.

http://www.microsoft.com/technet/prodtechnol/exchange/2003/articles/e2k3-e12hardware.mspx

With the release of exchange 2007 comming late this year or early next year, you should plan on a machine that can handle both.

The main difference between 2k3 and 2k7 is 2k3 usese a 32 bit processor and 2k7 will run only on a 64 bit processor.

Also if you can not wait for the release of 2k7 and go for 2k3 at the current time, make sure you buy it as an open license with software assurance. This will allow free upgrades to new versions with in 1 year of purchase. It needs to be done on both the server license and CAL's.

I work for a reseller so I can try and get more info if you like. Hope this helps.