VSS Application Compatibility

When developing your own VSS application, you should observe the following guidelines and restrictions. You may find it helpful to refer to the sample code for VSS requesters, providers, and writers that is provided in the Microsoft Windows Software Development Kit (SDK).

Windows Server 2003 R2, Windows Server 2003 and Windows XP: VSS is available in the Volume Shadow Copy Service 7.2 SDK, which you can download from https://www.microsoft.com/download/details.aspx?id=23490. Note that the 64-bit vssapi.lib files in the directories under the Win2003\Obj directory can be used for the 64-bit versions of Windows Server 2003 R2, Windows Server 2003, and Windows XP. This SDK also provides sample code for VSS requesters, providers, and writers.

Compiling VSS Applications

When developing a requester, such as a backup application:

• Include the following headers:

  Vss.h
  VsWriter.h
  VsBackup.h

• Link the following library:

  VssApi.Lib

When developing a writer:

• Include the following headers:

  Vss.h
  VsWriter.h

• Link the following library:

  VssApi.lib

Supported Configurations and Restrictions

The following list describes supported configurations and restrictions:

• VSS is provided and supported on versions of the Windows operating system beginning with Windows XP.

• The following table summarizes compatibility information across Windows versions. Note that if a VSS application is "compiled for" a specified Windows version, this means that the application was compiled using the header files and libraries that are specific to that version.

  Note

  Hardware providers will run only on Windows server operating system versions. They will not run on Windows client operating system versions.

  Note

  In the following tables, Windows Server 2008 with Service Pack 2 (SP2) should be considered the same as Windows Server 2008. For more information about Windows Server 2008 with SP2, see https://go.microsoft.com/fwlink/p/?linkid=178730. Windows Server 2003 R2 should be considered the same as Windows Server 2003.

  Note

  If a VSS application is compiled for Windows Server 2003 or later, it will also run on later versions of Windows.

• All 32-bit VSS applications (requesters, providers, and writers) must run as native 32-bit or 64-bit applications. Running them under WOW64 is not supported.

  Windows Server 2003 and Windows XP: Running 32-bit VSS requesters under WOW64 is supported, but not for system-state backups. Running 32-bit VSS providers and writers under WOW64 is not supported. Support for running 32- bit requesters under WOW64 was removed in Windows Vista and subsequent versions.

• A shadow copy that was created on Windows Server 2003 R2 or Windows Server 2003 cannot be used on a computer that is running Windows Server 2008 R2 or Windows Server 2008. A shadow copy that was created on Windows Server 2008 R2 or Windows Server 2008 cannot be used on a computer that is running Windows Server 2003. However, a shadow copy that was created on Windows Server 2008 can be used on a computer that is running Windows Server 2008 R2, and vice versa.

• To support shadow copies, a system running VSS must have at least one NTFS file system. This file system will host the shadow copy's "diff area." For more information, see System Provider.

• Given the presence of one NTFS file system, and given the appropriate choice of context (see Shadow Copy Context Configurations), any supported local file system can be shadow copied.

• You can make shadow copies only for locally mounted file systems. Remote shares and other cross-mounted file systems cannot be shadow copied by the system that mounts them. These file systems can be shadow copied only by the systems that serve out the file systems.

• Writers and requesters should specify only local resources. Local resources are sets of files whose absolute path starts with a drive letter, and the drive letter cannot be associated with a mounted folder on a remote share.

• The maximum number is of software shadow copies for each volume is 512. However, by default you can only maintain 64 shadow copies that are used by the Shadow Copies of Shared Folders feature. To change the limit for the Shadow Copies of Shared Folders feature, use the MaxShadowCopies registry key.

• The Backup Components infrastructure does not support backing up cluster resources as writer components. To back up cluster resources, applications should assume that the path is local to a specified particular cluster node.

• [!Note]

  Microsoft does not provide developer or IT professional technical support for implementing online system state restores on Windows (all releases).

  When backing up and recovering system state, the recommended strategy is to back up and recover the system and boot volumes in addition to the files enumerated by the system state writers.

  Note

  System state writers are writers that have the VSS_USAGE_TYPE attribute set to either VSS_UT_BOOTABLESYSTEMSTATE or VSS_UT_SYSTEMSERVICE.