Introducing VSS Support › How VSS Support Works › Service Roles › Writers and Components › Writers

Writers

A Writer is part of a VSS-aware application or service that participates in a VSS backup in the following ways:

• Works with VSS to prepare the application or service’s data to be frozen
• Suspends writes to the original volume while the shadow copy is created
• Supplies a list of Components to include in the backup (and the restore) to VSS and the Requestor

To ensure that the data used to create the shadow copy is internally consistent, VSS informs the applications or services that control the files included in the backup to freeze. When an application or service is frozen, the state of the files under its control is consistent. It is the responsibility of the Writer to let VSS know when an application or service’s files are in a consistent state.

To ensure that this state does not change during the creation of a shadow copy, the Writers suspend the ability of the application or service to make changes to the volume serving as the source of the shadow copy. The application (or its Writer) ensures the consistency of its data at the time of the shadow copy. Work can continue as usual on the original volume, but no changes are actually made to the data until after the shadow copy has been created.

A Writer is also responsible for supplying a list of Components to VSS and to the Requestor in the form of a writer metadata document. A writer metadata document is an XML file produced by a Writer that contains instructions for the Requestor, such as which Components are to be backed up, the backup and restore methods to be used, and a list of any files that should be excluded from the backup.

Note: Arcserve Backup does not support Writers under Windows XP. This is because some of the necessary Writer support in Windows Server 2003 is not included in the Windows XP operating system.