Topics | How To | Related Topics
When using VSS, write operations on the data being backed up can continue while these open files are copied and backed up, eliminating locked file conditions.
VSS can be enabled for backups of local volumes in both clustered and non-clustered environments. If the operating system fails to create a shadow copy of the data a traditional backup of the data will be performed, and a corresponding message will appear in the Event Viewer.
During a VSS backup, the free space needed on a volume for the shadow copy is related to the duration of the backup and the amount changes being made to the data objects (files, databases) that are being backed up. VSS snapshots capture and copy disk blocks that are being changed by other processes while the backup for a particular object is running. If the backup runs longer, or there is a lot of disk activity (files or databases being changed), this would cause VSS to copy more data blocks and therefore, use more disk space.
Microsoft Volume Shadow Service is the default, and only supported VSS software provider. The VSS software provider takes a snapshot of the source volume, database or file, which is then used to create backups or QR Volumes (when used with the Quick Recovery Agent).
VSS is supported by the following Windows iDataAgents:
VSS can be used to back up the system state and file system data. Enabling VSS on non-system state subclients allows you to back up Locked/Open Files.
VSS backups of the system state can be enabled on NTFS volumes as well as FAT volumes if there is at least one NTFS volume on the client computer. VSS is the preferred method of backing up the system state for clients of Windows iDataAgents that support VSS. For more information on system state backup with VSS, see VSS and Windows iDataAgents that support VSS on the System State page.
Incremental, Differential, and Full backups are supported when using VSS for file system data. VSS can be enabled for backups of NTFS and FAT volumes for file system data.
Locked database files are backed up in an inconsistent state and some system protected data will get backed up when "use VSS" for Windows File System iDataAgent is selected.
For example, you may have an Exchange database installed on the client. The Exchange database should not be backed up by the Windows File System iDataAgent because it will not be able to restore the database. Furthermore, this will increase your media usage. The Exchange database is likely already backed up by the Exchange Database iDataAgent.
If you have locked files that you would like to back up using VSS, we recommend that you create a subclient for them and enable VSS on that subclient.
Use of VSS on virtual servers controls the backup method for file system data only, not system state components; system state data is backed up by the physical node(s), not by the virtual server(s). Enabling or disabling VSS at the subclient level is described in VSS and Windows iDataAgents that support VSS.
Note that the physical cluster node will automatically filter all shared disk resources, and the virtual server will automatically filter all physical disk resources from data protection operations.
When configuring backup sets, you have the option of using the change journal or a classic file scan to detect which files have changed since the last backup. Note that if you use classic file scan and the check archive bit option together, then all backups by VSS on subclients will be converted to full backups. This is not an issue if you are only using VSS to back up the system state, which is always backed up in full. For backup of non-system-state files, you must use the change journal or deselect the check archive bit option if you want to perform incremental or differential backups.
The following must be done before using VSS.