Microsoft Volume Shadow Copy Service (VSS) is a feature of Microsoft Windows Server that coordinates among data servers, backup applications, and storage management software to support the creation and management of consistent backups. These backups are called shadow copies, or Snapshot copies.
VSS requirements
To use VSS with
SnapDrive for Windows, VSS requires the following:
- Your storage system must be running at least Data ONTAP 7.1.
Note: In versions of Data ONTAP prior to 7.3, snapshots taken after a shadow copy are locked due to the existence of LUN clones in the previous Snapshot copies, making them impossible to delete. In Data ONTAP 7.3, this restriction is removed, so SnapDrive is able to delete any Snapshot copies.
- The Virtual Disk Service must be running on your Windows host.
Overview of VSS
VSS coordinates Snapshot copy-based backup and restore and includes these additional components:
- VSS requestor
The VSS requestor is a backup application, such as the SnapManager for Microsoft Exchange application or NTBackup. It initiates VSS backup and restore operations. The requestor also specifies Snapshot copy attributes for backups it initiates.
- VSS writer
The VSS writer owns and manages the data to be captured in the Snapshot copy. Microsoft Exchange 2003 is an example of a VSS writer.
- VSS provider
The VSS provider is responsible for the creation and management of the Snapshot copy. A provider can be either a hardware provider or a software provider:
- A hardware provider integrates storage array-specific Snapshot copy and cloning functionality into the VSS framework. The Data ONTAP VSS Hardware Provider integrates the SnapDrive service and IBM N Series NetApp storage systems running Data ONTAP into the VSS framework.
Note: The Data ONTAP VSS Hardware Provider is installed automatically as part of the SnapDrive software installation.
- A software provider implements Snapshot copy or cloning functionality in software that is running on the Windows system.
Note: To ensure the Data ONTAP VSS Hardware Provider works properly, do not use the VSS software provider on Data ONTAP LUNs. If you use the VSS software provider to create Snapshot copies on a Data ONTAP LUN, you will be unable to delete that LUN using the VSS hardware provider.
The following figure shows how the modules communicate through VSS.
