There is now a better way to estimate likely hard disk life than Mean Time Between Failures (MTBF).
failure
There is already a substantial queue of organisations waiting to know how to create intensely viral events, and how to control them.
Most systems in everyday life had readily accessible fallbacks that you could rely on when the system of first choice was not available. We seem to have lost those now.
My employer bought new iMacs with extended wired keyboards. Last night one keyboard stopped working after a 15 minute power outage, and cannot be revived.
The real world performance of S.M.A.R.T. to warn of imminent drive failure is not as impressive as its claims, but here is how to get better use from it.
The Eclectic Light Company 