Union Filesystems

Jonathan ‘Wolf’ Rentzsch with an intro/overview of “union filesystems”, an interesting feature I’d never before heard about, which Mac OS X has inherited from BSD:

A union filesystem is kind of like onion-skin paper for your filesystem. You take one filesystem and “overlay” it on top on another. Your system will present one logical filesystem, featuring a combination of both filesystems in a very specific way.

★ Friday, 22 April 2005