You don't need NFS to run a de-deuping file system. PLan9's Venti has been ported to unix based user mode plan9

http://swtch.com/plan9port/man/man8/venti.html

I use it as a generale backup mechanism. I can save file systems from inside Qemu to it, from Inferno running on Windows, Linux stuff and I can write to it over the net (though it is in the clear so tunnel it).

http://maht0x0r.blogspot.com/2010/01/venti-on-linux-via-p9p....

You configure it so it will spit out certain sized data arenas suitable for burning to CD / DVD as the data is write once anyway.