IDedupReadFileCallback::OrderContainersRestore method (ddpbackup.h)

This method provides the application with the ability to influence the order of the pending reads that are required to retrieve the target file.

Given a list of container files that hold data for the restore target file, generates a list of container file extents in a sorted order that results in an efficient cross-container read plan from the backup store.

Implementation of this method by the application is optional.

Syntax

HRESULT OrderContainersRestore(
  [in]  ULONG                  NumberOfContainers,
  [in]  BSTR                   *ContainerPaths,
  [out] ULONG                  *ReadPlanEntries,
  [out] DEDUP_CONTAINER_EXTENT **ReadPlan
);

Parameters

[in] NumberOfContainers

Number of container paths in the ContainerPaths array.

[in] ContainerPaths

Array of paths to container files that must be read in order to restore the file specified in the IDedupBackupSupport::RestoreFiles call. Each element is a full path from the root directory of the volume to a container file.

[out] ReadPlanEntries

Pointer to a ULONG variable that receives the number of DEDUP_CONTAINER_EXTENT structures in the array that the ReadPlan parameter points to.

[out] ReadPlan

Pointer to a buffer that receives an array of DEDUP_CONTAINER_EXTENT structures.

Return value

This method can return standard HRESULT values, such as S_OK. It can also return converted system error codes using the HRESULT_FROM_WIN32 macro. Possible return values include the following.

Remarks

Given a list of container files that hold data for the restore target file, the application optionally generates a list of container store file extents in a sorted order that results in an efficient cross-container read plan. For a backup store located on tape, this would normally be in tape order.

In the case where a container is stored in multiple extents in the backup store—for example, as a result of an incremental backup sequence—the application may also return multiple container extents for each logical container file.

The application may return S_OK and NULL output parameters to skip the read plan optimizations. In this case, container read order will be chosen by Data Deduplication.

Requirements

See also

DEDUP_CONTAINER_EXTENT

IDedupReadFileCallback