Microsoft and Apple recommend that businesses deny certain iPhones, iPads and iPods access to Calendar items until the companies can clear up a problem that slows Exchange servers to a crawl when the devices try to synch.
The problem reveals itself to end users as an error message when they try to update items with Exchange Server 2010 that says "Cannot Get Mail" and "The connection to the server failed," according to a Microsoft support notification. The only option presented to users is to choose "OK," Microsoft says.
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More problematic for IT is that server CPU use jumps, affecting performance for all users. Microsoft describes the problem like this: "When a user syncs a mailbox by using an iOS 6.1-based device, Microsoft Exchange Server 2010 Client Access server (CAS) and Mailbox (MBX) server resources are consumed, log growth becomes excessive, memory and CPU use may increase significantly, and server performance is affected."
IOS 6.1 comes on iPhone 3GS, 4 and 5; fourth and fifth generation iPod Touch; iPad 2, third generation and fourth generation iPads; and iPad Mini. This makes for a major inconvenience for workers who use these devices at work primarily as a way to access emails and calendaring information.
Microsoft recommends that users facing this problem open trouble tickets with Apple to report the problem and diagnose what's causing the problem. "Apple and Microsoft are investigating this issue. We will post more information in this article when the information becomes available," Microsoft says.
The workaround is not to try accessing Calendar from the affected devices. If a user runs into the problem, rebooting the device may clear it up, Microsoft says. If not three other options might work: remove the Exchange account from the Apple device, wait half an hour and reinstall it; throttle the number of iOS devices that can access the server at the same time; and block all iOS devices from the server.
The second option will help protect server performance, but won't prevent the error messages, Microsoft says.
The support notification also advises how to detect whether the problem exists in a particular network.