How to Calculate Megacycles per Mailbox
Topic Last Modified: 2005-05-10
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 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.
Select a production server with a typical user load.
Use the System Monitor tool to monitor the Processor\% Processor Time counter over the peak two hours of server activity.
Calculate the average CPU usage (percent) from the data you obtain in Step 2.
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)