Dell NetWorker 19.9 Administration Guide

Overview of VSS

If the NetWorker Module for Microsoft is installed on the client computer, information in this chapter might be superseded by information in the NetWorker Module for Microsoft documentation. The NetWorker Module for Microsoft Administration Guide provides more information about the NetWorker Module for Microsoft.

Volume Shadow Copy Service (VSS) is a Microsoft technology that acts as a coordinator among all the components that create, archive, modify, back up, and restore data, including:

• The operating system
• Storage hardware
• Applications
• Utility or backup programs, such as NetWorker software

VSS allows for the creation of a point-in-time snapshot, or temporary copy, of a volume. Instead of backing up data directly from the physical file system, data is backed up from the snapshot. In addition, VSS allows for a single, point-in-time capture of the system state.

NetWorker uses VSS technology to create snapshot backups of volumes and exact copies of files, including all open files. Databases and files that are open due to operator or system activity are backed up during a volume shadow copy. In this way, files that have changed during the backup process are copied correctly.

Shadow copy (snapshot) backups ensure that:

• Applications can continue to write data to the volume during a backup.
• Open files are not omitted during a backup.
• Backups can be performed at any time, without locking out users.