Database Administrator's Guide

Volume Shadow Service (VSS) Support

The Volume Shadow Service (VSS) is a Microsoft technology built into Microsoft Windows operating systems starting from Microsoft Windows XP. This service allows taking manual or automatic backup copies or “snapshots” of a logical drive. Snapshots have two primary purposes:

• They allow the creation of consistent backups of a volume, ensuring that the contents cannot change while the backup is being made.
• They avoid problems with file locking.

By creating a read-only copy of the volume, backup programs are able to access every file without interfering with other programs writing to those same files.

FairCom Server provides VSS support through its VSS writer, which controls how FairCom DB data is set to a consistent state at the beginning of a VSS operation and maintain that consistency throughout the process.

The VSS writer is an integral component of the VSS support provided by FairCom DB. This component is supplied as a Windows dynamic link library (FairCom DBVSSWriter.dll) and can be optionally loaded by FairCom DB at startup.

This section discusses the following topics:

• VSS Configuration - Explains the configuration option that needs to be enabled when you are using VSS.
• VSS Diagnostic Logging - Explains the configuration option enables diagnostic logging using VSS.
• Dynamic API Interaction - Explains an API function can be used to change VSS configuration dynamically.