Neat! I didn't know the copy-on-write semantics for filesystems went back that far, the first I knew about was UnionFS[1][2], which features the same semantics in a larger package.<p>[1] <a href="http://unionfs.filesystems.org" rel="nofollow">http://unionfs.filesystems.org</a><p>[2] <a href="https://en.wikipedia.org/wiki/UnionFS" rel="nofollow">https://en.wikipedia.org/wiki/UnionFS</a>
NSE was an awesome development environment when it worked. Unfortunately, it often became corrupted and suffered a lot of down time. Just a touch too much cleverness for the systems at the time.