On an Exchange 2010 mailbox server, the Information Store service may become unresponsive and eventually dismount and/or be forcibly terminated. When this problem occurs, Exchange users keeps receiving an RPC error that Outlook is trying to contact Exchange. If you use Performance Monitor to view the values for Version Buckets Allocated under MSExchange Database -> Instances, you will find that the value increases constantly for one or more databases until those databases eventually fail.
Event 10027 may be logged when this problem occurs.
Event ID: 10027
Description: There are 5 RPC requests for the mailbox "<User>" on the database "<Database>" that have taken an abnormally long time to complete. This may be indicative of performance issues with your server.
This problem occurs because of a bug that causes the Information Store service to enter an infinite loop when a database page is updated.
A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next update that contains this hotfix.
To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note
In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.
This hotfix is scheduled to be included with Update Rollup 6 for Exchange Server 2010 Service Pack 2.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.