How to Calculate Megacycles per Mailbox


To calculate how many users a server can support, you must first determine your current usage profile. You can calculate a usage profile by using the following two key metrics together:

  • Megacycles/mailbox   Megacycles per second, per mailbox. The raw processor usage required per mailbox that is measured during the peak two-hour period on a production server.

  • IOPS/mailbox   Input/output per second, per mailbox. The raw database (DB) disk usage (input/output per second) required per user that is measured during the peak two-hour period on a production server. This metric does not include transaction log input/output (I/O) operations. For detailed steps about how to measure IOPS per mailbox, see How to Measure IOPS per Mailbox.

Before You Begin

Before you perform the procedure in this topic, consider the following:

If the users in a company are diverse usage requirements, you may have to measure usage profiles separately for different groups of users. For example, the sales engineers may have a different usage profile than the local marketing group. Having separate measurements is helpful only if the groups of users are significantly different.


To calculate megacycles/mailbox

  1. Select a production server with a typical user load.

  2. Use the System Monitor tool to monitor the Processor\% Processor Time counter over the peak two hours of server activity.

  3. Calculate the average CPU usage (percent) from the data you obtain in Step 2.

  4. Calculate your current megacycles/mailbox as described in the following formula:

    megacycles/mailbox = ((average CPU usage) × (speed of processors in megacycles) × (number of processors)) ÷ (number of mailboxes)