Topic Last Modified: 2006-07-13

The Microsoft® Exchange Server Analyzer Tool examines the Exchange Function Call Log (FCL), the Store.fcl file, for events that indicate ongoing cross-component calls from the Exchange Information Store service (Store.exe) to the Volume Shadow Copy Service (VSS) snapshot component.

Ongoing calls are requests from the Microsoft Exchange Information Store service (Store.exe) to other components that have not received a response at the time the Exchange FCL data is written to the Store.fcl file.

VSS is a set of COM APIs that implements a framework that enables volume backups to be performed when applications on a system continue to write to the volumes.

Microsoft Exchange Server 2003 uses the VSS that is included in the Microsoft Windows Server™ 2003 operating system to take volume shadow copies of Exchange Server 2003 databases and transaction log files.

A VSS snapshot is not fully independent of the original data. Generically, snapshots are created when you define a marker in time and make sure that the data can be rolled back to that time.

If the Exchange Server Analyzer finds that events in the Store.fcl logging file reflect ongoing calls from the Microsoft Exchange Information Store service (Store.exe) to the VSS snapshot component, the Exchange Server Analyzer displays a best practices message.

When cross-component calls from the Microsoft Exchange Information Store service (Store.exe) wait for a response, remote procedure call (RPC) threads can back up behind these requests and lead to Exchange Server performance issues such as delays in server responses to clients.

If a VSS snapshot was intentionally initiated within 20 seconds of the Exchange Call Trace logging collection, you can safely ignore this message as an indicator of an Exchange Server performance issue.

As a best practice, we recommend that you not overlap backup windows with online maintenance or peak-user demand intervals.

For More Information

For more information about VSS, see "Best Practices for Using Volume Shadow Copy Service with Exchange Server 2003" (