VSS: Volume Shadow copy Service 
(or Volume Snapshot Service)

Volume Shadow Copy Service is a Microsoft Windows service that coordinates various components to create consistent shadow copies of one or more volumes.

In Windows XP, Windows Server 2003 and Windows Vista Operating Systems, Volume Shadow Copy Service (VSS) provides a mechanism for creating consistent point-in-time copies of data known as 'shadow copies'.

With VSS you can backup files even if they are in use at the time of backup. If VSS is enabled (from the advanced options menu while creating a new backup schedule), StoreGrid will create a snapshot (read only copy) of the volume(s) corresponding to the configured folders/files and will thereafter backup the snapshot of the volume. The Volume Shadow copy helps StoreGrid create consistent backups, ensuring that the contents do not change while the backup is underway. This helps avoid problems typically associated with file locking; since StoreGrid uses a 'read-only' copy of the volume, it is able to access every file without conflicting with other programs writing to those same files!

This feature is especially useful in backing up exclusively locked files (of specific applications), such as the Outlook 'pst file' in case of Outlook backups. Please note that you do not need VSS functionality to backup databases (like SQL & Exchange) - StoreGrid includes powerful support for SQL Backup & Exchange Backup!

There is no extra charge for the Volume Shadow Copy functionality!

1. StoreGrid uses Microsoft's 'Volume Shadow Copy' Service (typically installed by default with the operating  system) to create the 'snapshot' for backup. Hence, StoreGrid needs the 'Volume Shadow Copy' Service to be configured with the service start type set to 'Automatic' or 'Manual'.

2. The Volume Shadow Copy Service needs at least 100 MB of free disk space.