[plug] low-power server: mini-itx or old laptop

mccabedj mccabedj at ucc.asn.au
Mon Feb 25 14:11:49 WST 2008

Gavin Chester wrote:
 > question is, what sort of hardware would suit best at minimal cost (<
 > $100) and low power consumption (<20W) for 'always on'?
 > Competing with that idea is the notion of pressing an older laptop into
 > service. I already have a suitable one so no outlay there. I realise
 > that it also is not fanless, but the cpu is low-power
 > (400MHzCel/6Gb/192Mb) so the fan hardly comes on - not forgetting it
 > will be idle most of the time. What sort of current would such a laptop
 > draw, btw?

Below 15.5 Watts I'd say, as you could switch the LCD off entirely. See
"The tests began with a Lenovo T61 laptop running the stock 32-bit 
Fedora 7 kernel... with kernel fixes and features, the power consumption 
of this laptop went from 21.06 Watts to 18.25 Watts; with 2 additional 
userspace fixes the power consumption ended up at 15.5 Watts"

If you have the laptop already, and it has a working battery, you can 
get PowerTOP to estimate its power consumption and give suggestions on 
how to cut back power consumption. Getting an actual amp-meter would be 
more accurate.

 > BTW: I realise there are numerous off-site hosting options, but a guy
 > wants to play, ok ;-)

Well, if you want to play...
You probably also want to leave the HDD in sleep mode for long periods 
of time; noatime/relatime and compcache may assist with this.  Actually, 
compcache would probably be especially useful in the driveless scenario.
Compcache uses a compressed ram device to mount swap on. There are 
benchmarks that show that this can give better overall performance than 
disk only swap. Additionally you don't have to wait for memory to spin up :)
   (Version 0.1 has a crasher bug, you may want svn instead)

John C. McCabe-Dansted
PhD Student, University of Western Australia

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