I have been following this thread closely, as I like the idea of suspending the MD. (Personally, I will probably leave the core on all the time, and thus my focus is the MD)
My motivation is twofold:
1) the power saving as others have mentioned,
2) reducing start up time for the MDs (time from no power to lmce started)
Currently my MD network boots in about 2 minutes, perhaps not much, but if I am to convince my wife to use LMCE to play DVDs, it has to start more like a DVD player (in a matter of seconds, not minutes).
So, partly motivated by this thread, I started out, trying to suspend my MD. Currently I can suspend it to RAM (also called S3), and restart it by wake-on-lan or by pressing the power button. (it restarts in about 3-4 seconds
On the MD;
Make sure uswsusp is installed (I installed both hibernate and uswsusp)
for more information how to set this up.
If you are using a nVidia card read this; http://en.opensuse.org/NVidia_Suspend_HOWTO
on how to suspend with nvidia. In short, add Option "NvAGP" "1" to the device section of xorg.conf and make sure no *vendor* agp modules are loaded (but agpgart is OK).
Then I run:
ethtool -s eth0 wol ug
and my MD suspends to RAM. The above is what my MD needed, you might not have to use the -f (force) flag on s2ram if your hardware is recognized as supported by s2ram. I needed to enable wake-on-lan with the ethtool command, as it would not wake on lan if not. (probably LMCE sets this up when shutting down).
As always, the whole suspend thing is very dependent on the hardware you have, so you may not be this lucky. Also make sure your BIOS power setting are correctly set up for suspend to ram.
(My hardware is a MSI mainboard with SIS961 chipset, a Realtek 8169 network card and a nvidia Geforce4 MX 440)
My next idea is to try to have the MD suspend to a flash disk ,to keep the MD as silent as possible and reduce the power use even more. But I have to buy a flash disk and CF to IDE adapter first.
What I would like now is to have the suspend options available from within LMCE. The power menu would be a good place to put something like this. But I also like the idea of having the power button on the remote suspend it. After pressing the power button, the user should get a confirmation question and an option to choose which suspend (ram/disk) he/she would like. Unfortunately, I have not got the slightest idea of how to add such a menu option. I hope someone else takes the challenge
Anyone have any data on the power usage in full-power vs. suspend to ram vs. suspend to disk vs. power-off ?