Retrieves the storage tier regions defined for a volume that supports data tiering.

To perform this operation, call the DeviceIoControl function with the following parameters.

   DeviceIoControl( (HANDLE)       hDevice,         // handle to device
                    (DWORD)        FSCTL_QUERY_REGION_INFO, // dwIoControlCode
                    (LPDWORD)      lpInBuffer,      // input buffer
                    (DWORD)        nInBufferSize,   // size of input buffer
                    (LPDWORD)      lpOutBuffer,     // output buffer
                    (DWORD)        nOutBufferSize,  // size of output buffer
                    (LPDWORD)      lpBytesReturned, // number of bytes returned
                    (LPOVERLAPPED) lpOverlapped );  // OVERLAPPED structure


hDevice [in]

A handle to the device. To obtain a device handle, call the CreateFile function.

dwIoControlCode [in]

The control code for the operation. Use FSCTL_QUERY_REGION_INFO for this operation.


Pointer to an input buffer of FSCTL_QUERY_REGION_INFO_INPUT. Currently the NumberOfTierIds should be zero and TierIds should be empty.

nInBufferSize [in]

Size of lpInBuffer in bytes.

lpOutBuffer [out]

A pointer to the output buffer, a FSCTL_QUERY_REGION_INFO_OUTPUT variably sized structure.

nOutBufferSize [in]

The size of the output buffer, in bytes.

lpBytesReturned [out]

A pointer to a variable that receives the size of the data stored in the output buffer, in bytes.

If the output buffer is too small, the call fails, GetLastError returns ERROR_INSUFFICIENT_BUFFER, and lpBytesReturned is zero.

If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl makes use of lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless.

If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If the hDevice parameter is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.

lpOverlapped [in]

A pointer to an OVERLAPPED structure.

If hDevice was opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped (asynchronous) operation. In this case, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways.

For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed. Otherwise, the function does not return until the operation has been completed or an error occurs.

Return value

If the operation completes successfully, DeviceIoControl returns a nonzero value.

If the operation fails or is pending, DeviceIoControl returns zero. To get extended error information, call GetLastError. The following table includes some common errors that can be returned from GetLastError when using the FSCTL_QUERY_STORAGE_CLASSES control code.

GetLastError return codeNotes
ERROR_ACCESS_DENIED The user does not have SE_MANAGE_VOLUME access.
ERROR_INSUFFICIENT_BUFFERThe memory pointed to by lpOutBuffer is not large enough to contain the requested information. The lpBytesReturned value will be zero.
ERROR_INVALID_PARAMETER A parameter was not valid; for example, hHandle is not a valid volume handle.



Minimum supported client

None supported

Minimum supported server

Windows Server 2012 R2



See also