The IOCTL_STORAGE_EJECT_MEDIA DeviceIoControl operation causes media to be ejected from a SCSI device.
BOOL DeviceIoControl(
  (HANDLE) hDevice,        // handle to device of interest
  IOCTL_STORAGE_EJECT_MEDIA,   // dwIoControlCode, control code of
                           // operation to perform
  NULL,                    // lpInBuffer is not used; must be NULL
  0,                       // nInBufferSize is not used; must be zero
  NULL,                    // lpOutBuffer is not used; must be NULL
  0,                       // nOutBufferSize is not used;
                           // must be zero
  (LPDWORD) lpBytesReturned,   // pointer to variable to receive
                           // output byte count
  (LPOVERLAPPED) lpOverlapped  // pointer to OVERLAPPED structure
                           // for asynchronous operation
);
If lpOverlapped is NULL (nonoverlapped I/O), lpBytesReturned is used internally and cannot be NULL.
If lpOverlapped is not NULL (overlapped I/O), lpBytesReturned can be NULL.
If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, this parameter must point to a valid OVERLAPPED structure. In this case, DeviceIoControl is performed as an overlapped (asynchronous) operation. If the device was opened with the FILE_FLAG_OVERLAPPED flag and lpOverlapped is NULL, the function fails in unpredictable ways.
If hDevice was opened without specifying the FILE_FLAG_OVERLAPPED flag, this parameter is ignored and the DeviceIoControl function does not return until the operation has been completed, or until an error occurs.
If the operation succeeds, DeviceIoControl returns a nonzero value.
If the operation fails, DeviceIoControl returns zero. To get extended error information, call GetLastError.
IOCTL_STORAGE_EJECT_MEDIA may or may not be supported on SCSI devices that support removable media.
  Windows NT: Requires version 4.0 or later.
  Windows: Unsupported.
  Windows CE: Unsupported.
  Header: Declared in winioctl.h.
Device Input and Output Overview, Device Input and Output Operations, DeviceIoControl, IOCTL_DISK_MEDIA_REMOVAL, IOCTL_DISK_LOAD_MEDIA