>So with such a high MTBF that you quote, do you put a backup >card in your secondary memory slot? > >My guess is yes, because you know there is more to reliability >than lab testing of components.
Yes, but that was not my point. The question asked related to the backup card being excessively used since it wasn't swapped out at all. My point is that with respect to the higher use that the backup card would get, it's rather lost in the noise.
With respect to do cards fail? Absolutely, and at the second worst time possible (at the worst time you will have prepared, so it's the second worst you need to worry about )