Volume Shadow Copy Service framework

Data Protection for Microsoft Exchange provides software and hardware vendors with a common interface model for generating and managing snapshots.

The Microsoft VSS service manages and directs three VSS software components that are used during VSS operations: the VSS writer, the VSS requestor, and the VSS provider. The VSS requestor is the backup software. The VSS writer is the application software. Examples of application software include Microsoft Exchange Server and Microsoft SQL Server. The VSS provider is the specific combination of hardware and software that generates the snapshot volume.

VSS writer
The VSS writer for the Microsoft Exchanger Server is the Microsoft Exchange Writer. The Microsoft Exchange Writer is provided by the Microsoft Exchange Information Store service or the Microsoft Exchange Replication service.
VSS requestor
The Tivoli® Storage Manager backup-archive client serves as the VSS requestor component and communicates with Microsoft VSS services to access data and create volume shadow copies. Because the Tivoli Storage Manager backup-archive client acts as the VSS interface, features such as LAN-free backup, client-side deduplication, data encryption, and data compression, are available. These feature are enabled by setting certain options that are defined in the backup-archive client options file.
This application initiates a snapshot operation. The application sends a command to the VSS service to create a shadow copy of a specified volume. The VSS requestor is the Tivoli Storage Manager backup-archive client.
VSS provider
This application produces the shadow copy and also manages the volumes where the Exchange data is located. A provider can be a system provider such as the one that is included with the Microsoft Windows operating system. It can also be a software provider or a hardware provider such as one that is included with a storage system.

VSS hardware providers require installation and configuration, including the installation of all required fix packages. For instructions, see the documentation for the VSS hardware provider.

For more information about VSS technology, see this Microsoft Technical Reference document: How Volume Shadow Copy Service Works.