Unit tests and fault injection tests catch a different but overlapping set of errors. Chaos Monkey is a terrific idea and I commend Netflix for implementing it early on. If you're not willing to randomly kill hosts then you're not confident that your distributed system really works.

This excellent paper[1] by James Hamilton (then MS, now AWS) recommends never doing clean shutdowns on applications - just kill them. Unless you have a lot of persistent state to manage this is a great idea. If it takes hours to migrate multiple TB off your storage host, maybe not such a good idea.

1. http://www.usenix.org/event/lisa07/tech/full_papers/hamilton...