[SATLUG] powersaving with Linux desktops

travis+ml-satlug at subspacefield.org travis+ml-satlug at subspacefield.org
Sun Sep 5 19:42:21 CDT 2010

Did some quick back-of-envelope calculations on SATA drives and found
they use negligible power...

~9W for a particular 7200rpm 500GB SATA-II drive.

(12 * 0.56 + 5 * 0.48) = 9.12

Converting to kWHr per month: multiply by 0.72 (30 * 24 / 1000)

Multiply by cost per kWHr: $0.05 in SA, $0.39 in CA

Then double to include cooling costs and inefficiencies in PSU.

Comes to ~$6/mo for me, less than $1 for you.

So, if you're going to go SSD, then do it for reasons other than cost
(performance, mobile computer battery life, lack of noise).

Tips on using SSDs:

Here's a tool for figuring out what processes are using (CPU?) power:
I imagine that's mostly useful on laptops.

Now, since we've ruled out HDDs, it seems the CPU is the main culprit.

The easiest solution would be to suspend (to RAM) or hibernate (that
is, save RAM to disk).

I tried suspend-to-RAM and had these problems on both XP and Linux
1) HDDs wouldn't spin back up
2) DVI cards wouldn't wake up monitors

Anyone fixed these?

Further, if I choose "suspend to RAM" or "hibernate" from the log-off
menu on Ubuntu, it just starts my screen saver.  WTF?

Oh... apparently I needed to set the "powersave" profile under power
management settings.  That controls what that "button" does.

I tried it on my desktop... it simply hung my system, with no obvious
way to restart it.

Upon restarting, it failed to get on the network -- apparently
something disabled the network interface too.  Very annoying.

Anyone else interested in figuring this out, or know the answers?
It asked me for my race, so I wrote in "human". -- The Beastie Boys
My emails do not have attachments; it's a digital signature that your mail
program doesn't understand. | http://www.subspacefield.org/~travis/ 
If you are a spammer, please email john at subspacefield.org to get blacklisted.
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