low power linux PC?

[V. Alex Brennen]

On Sun, 2008-04-06 at 22:07 -0400, Peter Dobratz wrote:

> For the backup server, I want to setup a separate box, probably
> running Debian.  As the primary purpose of this computer is just to
> store the backups, my primary feature consideration is power
> requirements.  Is there anything out there that can run Linux, have a
> few 250 GB or greater hard drives, and run on around 50 Watts or less?
>  It can be a headless box that I ssh into.

For a similar solution, I plug an external SDD (Spun Down Disk)
drive into a Dell portable.  As for a low power system that
runs Linux,  I've used disk-less fan-less boxes in the past
that were similar to these:

http://www.norhtec.com/products/index.html

I used them for network monitoring in NOC's running openssh,
wireshark, tcpdump, and iperf, on them.  The company that
made the particular brand, which was StrongARM based, that
I had used back then is no longer in business.

As for the external SDD drive, I have a Fantom External USB
Drive (Fantom Titanium-II TFD500U16 500GB 7200 RPM 16MB
Cache USB 2.0 External). In addition to spinning down when
not in use, it is also fan-less.

After ten minutes of inactivity the drive goes into low power 
mode.  It automatically reactivates when any file systems that
exist on it are accessed.  I power off the drive when I'm not 
using it in order to save additional energy.  But, because my
backups (database exports) can take some time to download over
my cable modem I'll often go to sleep after starting the
back-up process and shut off the drive in the morning.

I'm not sure about the watt consumption on the device since I
don't have access to a Kill-A-Watt type meter.  But, it seems
minimal.  Aside from a portable drive drawing power over USB,
as some one else mentioned, I think it's as low as you'll get
for a reasonable cost given what you're trying to do.

One note of caution regarding my set-up.  Since the Fantom 
drives are fan-less, they rely on the metal case to dissipate 
the heat generated by the disk drive.  I've heard some people
say that their drives have had early failures, possibly 
due to over heating.  I've had my drive for almost a year
with no problems.  But, I have a second drive of the same
model that I replicate to just in case my luck runs out.

The Broad Institute has a very large array of SATA-II drives
(a full rack) that rely on Spun Down Disk technology to 
conserve power.  They have been very happy with the
technology at that scale.  That's what convinced me to try
it out at home.

A higher cost but much lower power solution would be a
Flash Memory based storage device.


         - VAB
-
V. Alex Brennen                vab at mit.edu
UNIX Systems Administrator         x3-9327
MIT Libraries          http://vab.mit.edu/