One of the drawbacks imposed by BES is it forces IT to over-engineer their Exchange infrastructure to support the additional load created by BES. This includes paying close attention to the rate at which device usage is growing to make sure BES does not overload Exchange. In addition, BES requires a SQL Server (or SQL Express) database to keep track of the device state and licensing information for end users. Finally, BES and SQL cannot be installed on an Exchange server, which creates a need for additional server hardware or virtual machines. This translates into additional capital and operational costs.
BES also imposes a significant impact on Exchange's storage subsystem. When designing an Exchange server, one of the first calculations that must be made is IOPS (input/output per second). This determines how many disks will be required to support the load of a given number of users. Users of the Exchange 2010 Mailbox Server Role Requirements Calculator may have noticed a box called the "IOPS Multiplication Factor," which calculates the additional overhead that BES causes. On average, this overhead is three to four times the load of a single Exchange user.
As an example, an Exchange system for 10,000 users, of which 2,000 are BlackBerry users, would require IOPS of 16,000 mailboxes or more. This also translates to increased hardware and operational costs.
Microsoft ActiveSync technology allows mobile devices to synchronize data with an Exchange server. It has been around for a long time, but is not as widely deployed as BES because more business class users have chosen the BlackBerry device. This has changed in the past two years since iPhone and Android licensed ActiveSync from Microsoft (See ActiveSync Logo Program).
CLEAR CHOICE TEST: How to protect smartphones and tablets