Thanks for the good reminder, Steve, and the links.

This may be covered in the links (haven't read them yet), but I recall reading a similar topic where it mentioned that large companies such as Google invest in a huge amount of what they call commodity hardware -- decent but not top of the line equipment that is designed to be replaced when it fails, rather than a system where all the eggs are in one basket of a single high-end setup. Still requires a large budget, but it does make sense from a disaster mitigation point of view.

Also -- and I am by no means a math expert, so please excuse any errors -- my understanding of the failure rates of systems is that the chance of a failure on any given day for modern equipment may be quite small, but the chance of failure over a longer time is almost certain. So it's only a matter of time before parts fail. I guess it's only a short step from that realization to the realization that if you don't really know when the part will fail, you always need to be ready for it to fail and have a backup plan to handle it.

Just my two cents....

- webrunner