"the power used to start it up is only equivalent to a couple of seconds' worth of operation"
The argument is not that the power saved by continuous operation is greater than the power used by the startup, but that the initial surge on power up is what usually takes out a weakened electrical component. Personally, I'm for shutting unused systems down both to save both electricity and to relieve heat-related stress and mechanical wear, which in my humble opinion out weighs the advantages of avoiding the power on surge by leaving a system unnecessarily operating continuously.
Now having said that, when I was doing network services (both for other companies and as a systems consultant) working with Novell servers where it was not uncommon to be called in to do maintenance on a system that had been running for more than a year straight, it was standard practice to ALWAYS shut down, power down and then restart the server BEFORE touching it in any other way. You'd be surprised how many times a machine that's been running without a hitch for a year and a half straight fails to restart properly after a power off, even if it's been working just fine up to that point. And of course, it's much easier to convince the customer you didn't break it when he's in the room and has seen that all you've done is shut down, power down, and power back up.
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