IVdsDrive::QueryExtents method (vds.h)

Article
02/09/2023

[Beginning with Windows 8 and Windows Server 2012, the Virtual Disk Service COM interface is superseded by the Windows Storage Management API.]

Returns an array of the extents on a drive, including both allocated and unallocated extents.

Syntax

HRESULT QueryExtents(
  [out] VDS_DRIVE_EXTENT **ppExtentArray,
  [out] LONG             *plNumberOfExtents
);

Parameters

[out] ppExtentArray

A pointer to the array of VDS_DRIVE_EXTENT structures passed in by the caller. Callers must free this array by using the CoTaskMemFree function.

[out] plNumberOfExtents

A pointer to the number of drive extents returned in the VDS_DRIVE_EXTENT structure.

Return value

This method can return standard HRESULT values, such as E_INVALIDARG or E_OUTOFMEMORY, and VDS-specific return values. It can also return converted system error codes using the HRESULT_FROM_WIN32 macro. Errors can originate from VDS itself or from the underlying VDS provider that is being used. Possible return values include the following.

Return code/value	Description
S_OK	The extents information was returned successfully. For a drive without extents, the array is empty, the value of plNumberOfExtents is set to 0, and the value of ppExtentArray is set to NULL.
VDS_E_PROVIDER_CACHE_CORRUPT 0x8004241FL	This return value signals a software or communication problem inside a provider that caches information about the array. Use the IVdsHwProvider::Reenumerate method followed by the IVdsHwProvider::Refresh method to restore the cache.
VDS_E_OBJECT_DELETED 0x8004240BL	The drive object no longer exists.
VDS_E_OBJECT_STATUS_FAILED 0x80042431L	The drive is in a failed state, and is unable to perform the requested operation.
VDS_E_ANOTHER_CALL_IN_PROGRESS 0x80042404L	Another operation is in progress; this operation cannot proceed until the previous operation or operations are complete.
VDS_E_NOT_SUPPORTED 0x80042400L	The subsystem does not support this method.

Remarks

A drive can contribute extents to any number of LUNs, and these LUNs can be unmasked to any number of different computers on the network. Use the IVdsLunPlex::QueryExtents method to see all the extents of a LUN plex.

The LunId member of each VDS_DRIVE_EXTENT structure specifies the GUID for the LUN to which each allocated extent contributes. Consequently, you can use the result of this method to determine the number of LUNs to which the drive contributes by counting the number of distinct LunId values returned in ppExtentArray.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	vds.h
Library	Uuid.lib