If activity for a file system becomes so extensive that accesses are slow, take one of the following actions:

• Move the file system to a volume chosen for speed because it has, for instance, a faster channel or buffered controller.
• 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 structure of the file system.