This issue has already cost me 8 hours of valuable time.
How to make Exchange Server almost unresponsive with your Android phone (in my case Sony Xperia go)?
- run update to Android version 4.0.4
- make sure you have a lot of contacts (1100++ in my case)
- synchronize your contacts (via Microsoft Exchange ActiveSync requests with a server)
Exchange Server will become very slow, because the W3wp.exe process that is running under the MSExchangeSyncAppPool will use 100% of the CPU time.
This issue occurs when the mobile device tries to synchronize many contacts in a single request.
This synchronization request is frequently an unexpected POST of all the contacts that are on the mobile device. Exchange Server tries to validate the XML schema for each node for all the contacts. This may cause multiple memory allocations and excessive Microsoft .NET garbage collection.
In my case, the amount of (duplicated) contacts multiplied quickly from 1100 to 63,000 in a couple of hours.
http://support.microsoft.com/kb/2711053
Temporary solution:
- beg the user to switch of synchronization of contacts and keep it OFF
- restart Exchange Server services after the user has switched off contacts synchronization
