I agree, but we are talking about comparitive numbers - in my experience, the shared external storage infrastructure, (or even internal, non-shared storage) is more likely to suffer a failure than the server itself. One always has to try and consider every possibility, but the more likely a scenario is, the more weight has to be given to mitigation. I can't see how you would set up a system that was able to survive a storage outage, without it also being able to survive a server outage, so what's the point?