Eric ... several thoughts ... DML supports either producing a copy that shares or does not share.
Another good candidate for sharing is /opt. Sharing /usr is something Sun did for years before Linux arrived. Their use of shared /usr is one argument I put forward in favor of shared /usr. The problem Linux has is a culture of single systems leading to packaging and package handlers (RPM) where shared /usr is ... just something off the radar, something no one thought of. I found in early research that a whopping 90% of the "system" is static content. That is, when not counting for such things as a roomy /var or /home or other obvious growing filesystems, only about 10% of the system needed to be read-write non-shared, and most of that was because of static and non-static mixed in the same directory (like /etc, or how /bin, /lib, and /sbin are physically in the root FS). So sharing /usr is, to me, an obviously desirable thing. And with the weight of Solaris behind sharing /usr, there's strong precedent for it. I hope this helps. -- R;
