A more recent version of the COPS system is described here: http://www.cs.princeton.edu/~wlloyd/papers/eiger-nsdi13.pdf

Github for the more recent system: https://github.com/wlloyd/eiger

You can find the first author's posters and talks on the subject of scalable casaully-consistent storage here: http://www.cs.princeton.edu/~wlloyd/research.html