raph at mankin.org.uk
Sun Jun 7 12:59:15 BST 2009
On Sun, 2009-06-07 at 12:13 +0100, Duncan Garland wrote:
> I wonder if the problem can be approached from the other end. I wonder if
> there is a design standard (ISO or such like) which states that a
> manufacturer should aim for an MTBF of whatever.
> I'll let you know if I find anything.
MTBF, when quoted, is largely meaningless. The figures are computed,
purely theoretical. No-one actually runs a sufficiently large number of
items for long enough to get meaningful statistics. If they did, they
would miss the market.
Imagine having to run, say, 10000 disk drives for five years in order to
get meaningful MTBFs before you could put them on sale.
Only people like Google, Microsoft or Yahoo actually have sufficient
data, and all they can tell you that is *useful* is that some
manufacturers are, in the long term, better than others. Nothing about
models that are not obsolete.
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