BlackBerry cause additional overhead on exchange server

Do you know how much extra I/O overhead BlackBerry server will have impact on the Exchange server? Do you know how BlackBerry is design to talk to exchange server. The BlackBerry Enterprise Server connects to the Microsoft Exchange Server using the Messaging Application Programming Interface (MAPI) protocol. MAPI was designed to function on LAN connections, not WAN connections.

• Below information is taken from TechNet and explaining the overhead with RIM.
  

In Exchange 2000 and Exchange 2003, users that have BlackBerry devices place additional demands upon the server. In the field, many customers see a two to four fold increase in database disk I/O. For more information, see the RIM whitepaper.

BlackBerry users cause additional overhead that affect the database IOPS of a server. When RIM tested 1000 BlackBerry enabled MMB2 users with BlackBerry Enterprise Server 4, they saw database IOPS increase by a factor of 3.64 over the standard MMB2 user without BlackBerry. This factor could be significantly smaller or larger depending on how BlackBerry devices are used in the environment. The BlackBerry test included: 10 synchronization commands; two memo adds, one modify, one delete; and four task adds. Actual BlackBerry device use will not be this constant, causing a lesser or greater affect on actual IOPS.

For a mail system consisting of 2,000 heavily used mailboxes, of which 500 are BlackBerry enabled, a total of 3820 IOPS is projected on the database volume. The formula to calculate this is:

Estimated BlackBerry IOPS per User for User Type × Number of Users

In this example, 1.0 IOPS × 2,000 mailboxes=2,000 IOPS. If 500 of those users have BlackBerry devices, then those 500 users add 500 mailboxes x 3.64 IOPS=1820 IOPS, or 3820 total IOPS.

Using a conservative ratio of two reads for every write (66% reads to 33% writes), you would plan for 2,546 read I/O and 1,273 write I/O requests per second for your database volume. Every write request is first written to the transaction log file and then written to the database. Approximately 10 percent of the total 3,820 IOPS seen on the database volume will be seen on the transaction log volume (10 percent of 3,820 is 382 IOPS); 1,273 write I/O requests will be written to the database. See the Performance and Scalability guide for in depth strategies for properly calculating your server size.

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