thanks. From how i understand that works the file structure will be maintained until the first disk is full, from then on any changes will be on a different disk. What i was really wanting was to set up my file structure by placing the root folders on different drives and then drivepool filling those root folders in a structured way until there is no room left on that drive. This way the drives can mirror other drives to a greater extent. Im using drivpool as a backup. So i have 4 drives mirroring 3 main ones that are not part of the pool. I would hve like to keep the backup drives as close to a mirror of the main drives as a possible until they arent big enough and drivepool THEN spans the data amonst the rest of the pool.