IDedupReadFileCallback::OrderContainersRestore method (ddpbackup.h)

Article
02/22/2024

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

Requirement	Value
Minimum supported client	None supported
Minimum supported server	Windows Server 2012
Target Platform	Windows
Header	ddpbackup.h