"At some point in the next few years we are going to start getting HDD
failures on our blade server. It has ~30 hard drives plugged into it
after all (and ~12 SSDs as well). When that begins to happen I will
probably do a wholesale replacement of all HDDs with SSDs. Once that
is done I really expect failure rates to drop to virtually nil for the
next ~20-30 years. And the blade server is so ridiculously fast that we
probably won't have any good reason to replace it for at least a decade,
or ever (though perhaps we will add a second awesome blade server at
some point, who knows?)."
That's taking the long view. :-)