Reducing the size of the file system

If the file system becomes too big for the volume, you can try to reduce the size of the file system:

Create a new file system on another volume and move some files from the full file system to the new file system. Mount the new file system onto the previously full file system.
Move a subtree from the active file system into a new file system on a different volume. Mount the new file system onto the now-empty directory that was the head of the subtree. Accesses are divided between two volumes.
Moving a subtree, rather than individual files, retains the hierarchical structure of the file system.