Date: Wed, 7 Jun 2000 16:55:54 +0200 From: Stefan `Sec` Zehl <sec@42.org> To: Ollivier Robert <roberto@keltia.freenix.fr> Cc: freebsd-mobile@FreeBSD.ORG Subject: Re: spinning down the drive Message-ID: <20000607165554.A8830@matrix.42.org> In-Reply-To: <20000606234343.A68786@keltia.freenix.fr>; from roberto@keltia.freenix.fr on Tue, Jun 06, 2000 at 11:43:43PM %2B0200 References: <20000606161140.A8303@dophnic.yi.org> <20000606234343.A68786@keltia.freenix.fr>
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On Tue, Jun 06, 2000 at 11:43:43PM +0200, Ollivier Robert wrote:
> According to Derek Moeller:
> > Is this possible? Are there significant hard drive power gains
> > if it's spun down in a laptop?
>
> Considering that you have a sync(2) every 30s (w/o softupdates) and even more
> of them with softupdates, I don't see what you'd gain.
>
> I'd say it takes more power to restart the drive every N seconds than letting
> it spin.
>
> I may be wrong but I don't see it useful.
On 2.2.x Systems you could increase the sync interval. Which I set to 3
hours. I then typed 'sync' whenever the hard drive spun up after a read.
That way I got a significant longer uptime from my battery.
Unfortunately on 3.0 and greater you can't defer writes that much.
I've been working on a patch to defer writes as long as possible, which
meant to get confident with kernel-hacking at first :). It's
unfortunately still far from finished.
While we're at this point. Is there a way to figure out if a given disk
is spinning or sleeping?
CU,
Sec
--
In 1968 it took the computing-Power of 2 C-64 to fly a rocket to the moon.
Now, 1997 it takes the Power of a Pentium 133 to run Microsoft Windows 95.
Something must have gone wrong.
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