IVssCreateWriterMetadata::AddAlternateLocationMapping method (vswriter.h)

Article
10/13/2021

The AddAlternateLocationMapping method creates an alternate location mapping for a file set.

Syntax

HRESULT AddAlternateLocationMapping(
  [in] LPCWSTR wszSourcePath,
  [in] LPCWSTR wszSourceFilespec,
  [in] bool    bRecursive,
  [in] LPCWSTR wszDestination
);

Parameters

[in] wszSourcePath

Null-terminated wide character string containing the name of the directory or directory hierarchy containing the files to be mapped.

The directory can be a local directory on the VSS machine, or it can be a file share directory on a remote file server.

The path can contain environment variables (for example, %SystemRoot%) but cannot contain wildcard characters.

There is no requirement that the path end with a backslash (""). It is up to applications that retrieve this information to check.

[in] wszSourceFilespec

Null-terminated wide character string containing the file specification of the files to be mapped.

A file specification cannot contain directory specifications (for example, no backslashes) but can contain the ? and * wildcard characters.

[in] bRecursive

A Boolean value specifying whether the path specified by the wszPath parameter identifies only a single directory or if it indicates a hierarchy of directories to be traversed recursively. This parameter should be set to true if the path is treated as a hierarchy of directories to be traversed recursively, or false if not.

For information on traversing mounted folders, see Working with Mounted Folders and Reparse Points.

[in] wszDestination

Null-terminated wide character string containing the fully qualified path to the directory where the files will be relocated.

The directory can be a local directory on the VSS machine, or it can be a file share directory on a remote file server.

UNC paths are supported.

Return value

The following are the valid return codes for this method.

Value	Meaning
S_OK 0x00000000L	The operation was successful.
E_INVALIDARG 0x80070057L	One of the parameter values is not valid.
E_OUTOFMEMORY 0x8007000EL	The caller is out of memory or other system resources.
VSS_E_INVALID_XML_DOCUMENT 0x80042311L	The XML document is not valid. Check the event log for details. For more information, see Event and Error Handling Under VSS.
VSS_E_OBJECT_NOT_FOUND 0x80042308L	The IVssCreateWriterMetadata::SetRestoreMethod method was not called before this method was called.
VSS_E_UNEXPECTED	Unexpected error. The error code is logged in the error log file. For more information, see Event and Error Handling Under VSS. Windows Server 2008, Windows Vista, Windows Server 2003 and Windows XP: This value is not supported until Windows Server 2008 R2 and Windows 7. E_UNEXPECTED is used instead.

Remarks

Windows 7, Windows Server 2008 R2, Windows Vista, Windows Server 2008, Windows XP and Windows Server 2003: Remote file shares are not supported until Windows 8 and Windows Server 2012. Writers support only local resources—sets of files whose absolute path starts with a valid local volume specification and cannot be a mapped network drive. Therefore, path inputs (wszPath and wszDestination) to AddAlternateLocationMapping (after the resolution of any environment variables) must be in this format.

This method can be called multiple times to add mapping for multiple files.

The combination of path, file specification, and recursion flag (wszPath, wszFileSpec, and bRecursive, respectively) provided to AddAlternateLocationMapping to be mapped must match that of one of the file sets added to one of the writer's components using IVssCreateWriterMetadata::AddFilesToFileGroup, IVssCreateWriterMetadata::AddDatabaseFiles, or IVssCreateWriterMetadata::AddDatabaseLogFiles.

The AddAlternateLocationMapping method should be called only after IVssCreateWriterMetadata::SetRestoreMethod is called.

A file should always be restored to its alternate location mapping if either of the following is true:

The restore method (set at backup time) is VSS_RME_RESTORE_TO_ALTERNATE_LOCATION.
Its restore target was set (at restore time) to VSS_RT_ALTERNATE.

In either case, if no valid alternate location mapping is defined, this constitutes a writer error.

A file can be restored to an alternate location mapping if either of the following is true:

The restore method is VSS_RME_RESTORE_IF_NOT_THERE and a version of the file is already present on disk.
The restore method is VSS_RME_RESTORE_IF_CAN_REPLACE and a version of the file is present on disk and cannot be replaced.

Again, if no valid alternate location mapping is defined, this constitutes a writer error.

An alternate location mapping is used only during a restore operation and should not be confused with an alternate path, which is used only during a backup operation.

For more information on backup and restore file locations under VSS, see Non-Default Backup And Restore Locations.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	vswriter.h (include Vss.h, VsWriter.h)
Library	VssApi.lib