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Re: low power PC

Miaoling Chiu wrote:
> I understand how to do downclocking by resetting
> jumpers. And I could install a LCD monitor, or
> just turn the monitor off when I'm away from the
> machine. What I don't understand though is how to
> power down a hard disk (or how to install without
> a hard disk). I've heard of people running Linux
> off a CD, floppy, zip or a ram disk, but seems to
> me like if would have to be a very minimalist
> system, and I don't know how you could run a
> server that way. But I'm open to any suggestion
> about how to cut power consumption to the
> bone. Any ideas? I don't need a very powerful
> server, but it should be capable of running
> Apache and Postfix all day - if that can be done
> without a hard disk, I'd appreciate some
> suggestions on how to set it up.
>  - Chiu Miaoling

Lots and lots of RAM. Find a motherboard that can hold a lot of RAM,
and fill it with all the maximum size DIMMs you can find. Then, on
boot, create a ramdisk and copy the critical bits to the ramdisk. But
if you make the ramdisk too large, you'll end up swapping to disk a
lot. So there's a balance to be had there. This is basically the
technique that a number of e-commerce sites use to improve
responsiveness of their systems. Just make sure you sync back to
physical disk from time to time. 

How busy is said server? If it has brief bits of activity, followed by
long idle spells, and you're in x86 land, you should be able to
twiddle the power management settings in your BIOS to control how
active the HDD (and other bits) are. I do this with one of my machines
at home. It's a little slow to wakeup, but once it does, it's very
responsive, and when I stop hitting it, it goes to sleep. 

Justin Wojdacki        
justin@chiplogic.com               (408) 350-5032
Communications Processors Group -- Analog Devices

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