Update 4/25/2011: Updated formula to reflect new guidance from MS. Added reference link for formula guidance from MS.
Determining the megacycles per core value of your Exchange Mailbox server platform is more of an art than a science. Though Microsoft provides instructions on how to do this, I thought they could use some massaging to make them more user friendly. To determine the megacycles per core value of your chosen server platform follow the steps below.
Calculating the formula’s values
New Platform per Core Value
- Open a web browser and go to www.spec.org or you can click here and go straight to Step 7.
- Select Results Search from the menu.
- Click Search. (No need to specify any value in the search field)
- Under Available Configurations at the top, select SPECint2006 Rates.
- Select Simple under Search Request Form.
- Click Go.
- Under Simple Request, choose the search value (e.g. Processor) and enter the search criteria (e.g. x5550).
- Click Execute Simple Fetch.
- Find the server and processor you are planning to deploy and take note of the Result value. For example, let’s say you are deploying a Dell PowerEdge M710 server with Intel x5550 2.67GHz processors (8 cores). The SPECint_Rate2006 Result value is 240. This translates to a a value of 30 per core (Result/# of cores or 240/8). This value is known in the formula as “New platform per core value“.
Baseline per Core Value
The platform used to determine the Storage Calculator baseline of 3300 megacycles is an HP DL380 G5 x5470 3.33GHz with 8 cores. This has a SPECint_Rate2006 Result value of 150, or 18.75 per core. This is known in the formula as “Baseline per core value“.
Calculate the total Megacycles per Core
To determine the megacycles of the new platform, we will use the following formula:
Megacycles per core = ((New platform per core value) * (Hertz per core of baseline platform)) / (Baseline per core value)
= 30 * 3333 / 18.75
= 5332 megacycles per core
Enter this value into the Megacycles/Core field under the Server Configuration section of the MS Mailbox Role Storage Calculator.
To calculate the total Mailbox Role CPU Megacycles requirement when hosting the Mailbox servers in a virtual platform add an additional 10% overhead for the host OS. IE: If your total megacycle requirements per server is 16000 then virtualizing the Mailbox role will increase that value to 17600 megacycles per server.
To calculate the megacycles per core value when virtualizing the Exchange Mailbox role use the hardware platform of your host server to determine the “New platform per core value”.
To determine how many cores you will need for your Client Acces, Hub Tranport and Global Catalog server use this table as a guide.
|Mailbox Role: Client Access Server Role||4:3|
|Mailbox Role: Hub Transport Server Role with Antivirus|
Mailbox Role: Hub Transport Server Role no Antivirus
|Mailbox Role: Global Catalog Server (x64)|
Mailbox Role: Global Catalog Server (x32)
For more detailed information on calculating server core ratios for the different Exchange server roles, see the Microsoft documentation at: http://technet.microsoft.com/en-us/library/dd346701.aspx.
For more information on the formula itself see the following post at: http://blogs.technet.com/b/exchange/archive/2010/09/14/3411025.aspx3,764 views