"running under continuous load for two solid weeks" is merely the beginning. You should really abuse it meanwhile. For example, every minute, shoot the current leader (master or whatever you call it) while under load. Watch another node take over. Then restart the killed node, (maybe from scratch). For this type of products, a monkey

http://www.folklore.org/StoryView.py?story=Monkey_Lives.txt

is a good idea, as it will generate new types of torture you never considered.