Richard Elling wrote:
Good question. If you consider that mechanical wear out is what
ultimately
causes many failure modes, then the argument can be made that a spun down
disk should last longer. The problem is that there are failure modes
which
are triggered by a spin up. I've never seen field data showing the
difference
between the two.
Often, the spare is up and running but for whatever reason you'll have a
bad block on it and you'll die during the reconstruct. Periodically
checking the spare means reading and writing from over time in order to
make sure it's still ok. (You take the spare out of the trunk, you look
at it, you check the tire pressure, etc.) The issue I see coming down
the road is that we'll start getting into a "Golden Gate paint job"
where it takes so long to check the spare that we'll just keep the
process going constantly. Not as much wear and tear as real i/o but it
will still be up and running the entire time and you won't be able to
spin the spare down.
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