Reflecting the large number of iPhones and iPads that are connected to Exchange mailboxes via ActiveSync, I received a lot of email after I posted a note on February 7 reporting the problems with excessive transaction log generation that Exchange servers experience after iOS devices are upgraded to iOS 6.1. Microsoft’s formal knowledge base article (KB2814847) on the topic is also available for your reading pleasure. Microsoft offers three ways to resolve the problem, including the creation of a custom throttling policy, which I do not cover here.
Ever since the problem appeared, people have been asking what to do to control these pesky iOS 6.1 devices. The problem can be a delicate matter because senior management are often fans of Apple devices and it wouldn’t go down well if IT suddenly imposed a blanket ban on iOS 6.1. The stress on Exchange would certainly ease if the rate of transaction log generation reduces but the stress level of iPhone users might increase if they were to receive a message from Exchange to tell them that their device is blocked.
Apparently Apple is responding by rushing a new build (6.1.1) out to address the issues noted with Exchange as well as some other problems with 3G performance and degraded battery life. The new version is being directed to iPhone 4S devices first. If you don’t want to wait for the new build to get to your iOS devices and are interested in the details of how to use ActiveSync device access rules to control access to iOS 6.1 (and other devices), fellow MVP Paul Cunningham has written up the necessary steps to put the blocks in place. A big health warning applies before any block is imposed: test, test, and test again.
Some correspondents have found that they can handle the problem by deleting the device partnership and forcing a complete resynchronization and indeed, this is one of the suggestions listed in KB2814847. It is reasonable to assume that this step causes the iOS mail app to use different code to synchronize the entire mailbox rather than just the meeting requests that seem to lie at the root of the problem.
A device partnership essentially links a mailbox and a mobile device and allows Exchange to track what happens with the device. You can see details of a partnership using the Get-ActiveSyncDevice command (works with Exchange 2010 and 2013) and you can remove a partnership with the Remove-ActiveSyncDevice command. Two small problems get in the way. First, you have to pass the identity of the partnership that you want to remove. Second, many users are associated with multiple partnerships because they use (or have used) multiple devices to synchronize with Exchange via ActiveSync.
Of course, forcing every single iOS device to resynchronize is neither good for user blood pressure nor your server, so it’s good to know what mailbox is linked to the problem. One good way of doing this is to run the Exchange User Monitor (ExMon) utility to monitor the demand that mailboxes are making on a server. The problem mailboxes will be easily seen as they are the ones that consume far more resources than any other mailbox. Another good suggestion is to use Microsoft’s Log Parser studio (this post provides good guidelines for what you need to do) to extract information from the IIS logs to focus on the misbehaving clients. Others have found that the ActiveSync Report script posted on EHLO is useful.
Whatever method you use to identify the mailboxes, take a note of their names and then run the Get-ActiveSyncDeviceStatistics command to confirm that they are using iOS 6.1 devices. If they are not, the excessive mailbox activity can only be accounted by their insertion of new set of batteries recently. For example, this command returns a list of the ActiveSync partnerships that are known for my mailbox:
Get-ActiveSyncDeviceStatistics –Mailbox Tredmond | Format-Table DeviceID, DeviceType, DeviceOS
DeviceOS will start with “IOS 6.1” for any device running iOS 6.1. DeviceID contains the identifier for the partnership that we need to remove, so an amended command will remove the partnership. Get-ActiveSyncDeviceStatistics returns all known partnerships for the mailbox, so the filter is absolutely needed to remove just the partnerships associated with iOS 6.1:
Get-ActiveSyncDeviceStatistics –Mailbox TRedmond | ? {$_.DeviceOS –match “iOS 6.1”} | Remove-ActiveSyncDevice
A polite phone call to the user might be in order to avoid the frantic help desk call that will ensue when they realize that their device needs to resynchronize.
Microsoft is also struggling with the same operational concerns over iOS 6.1 device with their Exchange Online service and have implemented throttles to ensure that problematic devices are blocked. Seems like the right approach to take – never let badly functioning devices (for hardware or software reasons) compromise the overall stability of a service.
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