How to Measure IOPS 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. For detailed steps about how to calculate megacycles per mailbox, see How to Calculate Megacycles per Mailbox.

  • 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.

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.

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

  2. Use the System Monitor tool to monitor Physical Disk\Disk Transfers/sec counter over the peak 2 hours of server activity.

  3. Calculate your current IOPS/mailbox as described in the following formula:

    IOPS/mailbox = (average disk transfer/sec) ÷ (number of mailboxes)


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