VSS Writer & SQL Writer Service

VSS Writer & SQL Writer Service

Background information

VSS

VSS is a framework that consists of a set of interfaces and structures that enable applications to perform backups of volumes while other applications use the data in these volumes.

VSS is included with Microsoft Windows XP and Microsoft Windows Server 2003.
Backup applications
A backup application is any Windows application that requests a snapshot backup be taken by using VSS. For example, the Windows NT backup application that is included with Windows is a backup application.

Writers

Writers are applications or services that store persistent information on disk and that cooperate with providers and requestors through the shadow copy interface. We will discuss the MSDEWriter writer and the SqlServerWriter writer in this article.

MSDEWriter:

The MSDEWriter writer is a VSS Writer for SQL Server. MSDEWriter is included with the VSS framework in Windows XP and Windows Server 2003. MSDEWriter works with SQL Server 7.0, SQL Server 2000, and SQL Server 2005.

SqlServerWriter:

The SqlServerWriter writer is a VSS Writer for SQL Server. SqlServerWriter is included with SQL Server 2005. SqlServerWriter only works with instances of SQL Server 2005.

SQL Server provides an API called Virtual Backup Device Interface (VDI) that enables independent software vendors to integrate SQL Server into their products for providing support for backup and restore operations. These APIs are engineered to provide maximum reliability and performance, and support the full range of SQL Server backup and restore functionality, including the full range of hot and snapshot backup capabilities.

A VSS writer (MSDE Writer) shipped with the VSS framework in Microsoft Windows XP and Microsoft Windows Server 2003. This writer coordinates with SQL Server 2000 and earlier versions to help in backup operations. With SQL Server 2005 installation, SQL Writer is the preferred writer, though MSDE Writer will continue to work and will be the default writer if installed and SQL Writer is not enabled. To start and use the SQL Writer, first disable the MSDE writer from enumerating SQL Server 2005 databases.

SQL Writer Service
http://technet.microsoft.com/en-us/library/ms175536.aspx
SQL Server 2005 connectivity and Volume Shadow Copy Service (VSS)
http://support.microsoft.com/default.aspx?scid=kb;EN-US;919023
VSS and SQL Writer (MSDEWriter) troubleshooting

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