Administrators can grow LVs (by concatenating more LEs) or shrink them (by returning LEs to the pool). The concatenated LEs do not have to be contiguous. This allows LVs to grow without having to move already-allocated LEs. Some volume managers allow the re-sizing of LVs in either direction while online. Changing the size of the LV does not necessarily change the size of a file system on it; it merely changes the size of its containing space. A file system that can be resized online is recommended in that it allows the system to adjust its storage on-the-fly without interrupting applications.