While Exchange sizing is neither brain science or rocket surgery, it sure can seem like a combination of alchemy, divination, and voodoo to those who are not extremely experienced in the subtle science and exact art that goes into Exchange for the enterprise. Fortunately, Microsoft’s Exchange team makes available a set of tools to help customers properly plan for and size their Exchange environments to best advantage. Two tools we want to revisit today are the Server Role Requirements Calculators for both Exchange 2013 and 2010. Both have recently been updated to bring improvements to the tools.
These calculators are actually very well thought out, multiple page Excel workbooks that can be downloaded for free from Microsoft’s website. Of course, they do require you to have Excel, but these days, if you are working with Exchange you almost certainly have Office. Who doesn’t?
The calculators walk administrators through planning the hardware for their Exchange deployments. They take into account roles, and look at things like CPU cores, memory, and disk configuration. You start with the input tab, and work your way through things like volume requirements, backup requirements, and replication requirements. There are a number of notes within the calculators that you need to take into consideration, like CPU. +/- 20% is a pretty big margin, and if you have antivirus software or archiving software, email to fax software, or use a third party backup solution, you need to account for the RAM and CPU requirements. The calculator is good, but it is only focused on Exchange. You need to cover anything else you are going to put on the server.
But be warned. Like almost all calculators, sizing tools, crystal balls, and Tarot cards, GIGO applies. You’re not familiar with the term GIGO? It stands for Garbage In, Garbage Out, and it’s amazing just how good these calculators can be when you give them real data, and how bad they can be when you SWAG stuff. If you don’t have baselines, be very careful about how you use these calculators and what kind of expectations you have from them. While many organizations are similar, no two are quite the same. What makes yours unique may be the difference between needed ten servers or twelve, or upgrading your bandwidth 20% or 30%. If you really don’t have any real data to go on, and can’t take the time to gather that data in order to use the calculators to their fullest, you might be better off piloting a handful of users taken from across the enterprise, standing up a minimum environment, and seeing how well it scales as you add users. If your sampling is random, it should be representative.
You can download the Exchange 2013 Server Role Requirements Calculator v5.6 from http://gallery.technet.microsoft.com/Exchange-2013-Server-Role-f8a61780/file/82543/1/E2013Calc5.6.xlsm. You can download the Exchange 2010 Server Role Requirements Calculator v20.6 from http://gallery.technet.microsoft.com/Exchange-2010-Mailbox-Server-Role-/file/82544/1/e2010Calc20.6.xlsm.