Slow VSS Snapshot Calls
Topic Last Modified: 2006-07-13
The Microsoft® Exchange Server Analyzer Tool examines the Exchange Function Call Log (FCL), Store.fcl file, for Volume Shadow Copy Service (VSS) snapshot component events that exceed a response time of 20 seconds.
Exchange FCL VSS component events represent Microsoft Exchange Information Store service (Store.exe) function calls to the VSS snapshot component.
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 file reflect a response time of more than 20 seconds for the SS snapshot component function calls from the Microsoft Exchange Information Store service (Store.exe), the Exchange Server Analyzer displays an error.
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 error 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.