Automatic means for spinning down disks available?

Yuri Grebenkin breath at
Wed Apr 11 10:46:50 UTC 2007

On Tue, 10 Apr 2007 21:06:15 -0400
Jules Gilbert <jules.stocks at> wrote:

> Boy, do I want answers too!
> We have HD's that run 24X7.  And I don't want to turn them off, I  
> just want them to sleep quietly until needed.  We have lot's of RAM,  
> thus plenty of cache space.
> Our machines are all blades.  (Does this matter?  I don't know.)   
> IBMs and Super-Micros.
> We spend zillions of bucks on electricity;  We use these machines  
> 24X7 now, but soon will only need them about 12 hours a day.  Is 24X7  
> operation the optimal strategy?
> What's the best course here, wrt electric costs, and wrt disk failures?

That's the point! Electric costs vs failures.
If financial side is the interest, - obvioulsy statistics and calculator.
My original question sounded like "what's the safest way".

Let's see:

An HD in full operation get definitely hot and hence (evidently) consuming
power. And then it turns to sleeping mode and becomes cooler... cooler...
Then (maybe) this process repeats all the time. Despite even cold turning on
stresses these permanent temperature differences can't be good.

Conclusion might be like this:

If one has certain amount of trusted drives and they are expected to sleep
reasonable time only a few times a day then one should save energy, thinking
of tuning wakeups and regular backup. The same with stations that rarely use
HDs and/or do their stuff (if any) using only RAM.

If a machine is under constant load, or expected to wake up once per several
hours it's better to leave it all in peace :). It seems somewhat hard to
estimate sleeping periods accurately in this case. And even huge cache can
be a reason for unexpected need in accessing a bit of disk data.

As Gary Kline said, slowing down drives could be a good idea in some
circumstances. There are so many user desktops running only a text processor
and... heating the air! What for? And there is more to it, these desktops
are everywhere and all of them together burn too much more energy resources
than server and development installations, like ones, I hope, we are talking
about. And I think that stability of latter ones is a concern (to serve the
rest of "production" teapots).

Finally, if one is using (it's highly encouraged!) FreeBSD at home to do all
sort of things, let's experiment with power savings too! Because the feature
must retain in OS and improve with overall experience and support.

- Yuri

> --jg
> On Apr 8, 2007, at 2:10 PM, Yuri Grebenkin wrote:
> > Just wonder if it's better for an HDD not to spindown at all.
> > Maybe it's safer to spin in peace than to park/launch?
> > What do you think?
> >
> >> Hello again all,
> >> 	I was wondering if there was an automatic, and possibly timed  
> >> means to
> >> spin down disks available in either ports or the base system, by  
> >> chance.
> >> 	Just trying to cut down on energy use, and increase my disks'  
> >> lives :).
> >> TIA,
> >> -Garrett
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