[mythtv-users] Discussion: system layouts to reduce power consumption

[Eloy Paris]

On Tue, Jul 28, 2009 at 10:58:38AM +1000, glenhawk at optusnet.com.au wrote:

> I am very conscious of power consumption and want to try and reduce
> it wherever possible. I already believe that using MythTV saves power
> in a way because it reduces the overall time that your AV gear is
> switched on. My concerns are now that in a house where you want access
> to MythTV on most if not all of your TVs how do you balance power
> consumption with functionality?

> With the prospect of 0.22 promising tunerless MBE and dynamic waking
> of SBE machines there have been suggestions of configuring light
> weight MBE systems to work with a NAS and SBEs with tuners in place
> of FEs (I have suggested such a layout myself). The idea being to
> minimise the number of systems on at any one time and to minimise the
> power consumption of each individual component.

> The other benefit that I am looking for is an "always-on" ability to
> remotely connect to my system at home (eg. MythWeb) or at the very
> least a scheduled "on-time" as you can set with MythWelcome.

> I have tried using Wake-On-LAN over the Internet to only switch on the
> MBE when needed but I couldn't get it through my router and even if
> I could I would have to quickly start recording something to prevent
> the system from shutting back down (perhaps if MythWeb could be made
> to hold MythShutdown it would be worth persevering to get WakeOnLAN
> working over the net... or maybe I just need to adjust the idle time
> to an ideal value).

> While I have been puzzling over the perfect layout I have become
> aware of the ARM based Beagleboard. I have even seen that someone has
> installed MythTV on one. I would be more than happy to allow a ARM
> based system to be always on running the MBE. It wouldn't have to do
> any processing just manage the database and SBE systems. I would then
> do one of two things...

> 1. put tuners in my frontends to make them SBEs recording to an "always-on" NAS
> 2. build a "MediaTank" SBE with lots of HDDs and tuners that would only come on for recordings or when an FE wakes it.

> Option #1 has two always-on systems (MBE and NAS) while option #2 only
> has one. If the NAS in option #1 is a PC running freeNAS you kind of
> "rob Peter to pay Paul" with respect to power consumption but if it is
> a dedicated NAS (eg. DLINK) then the extra power consumption may be
> negligible. If I only watched TV from one System then option #2 would
> be the best option because the "one-system" would be the "MediaTank"
> SBE but the fact that I have at least three systems to choose from to
> watch TV perhaps the NAS option would be more efficient.

> To confuse things further is it pointless to have a machine incapable
> of being a FE attached to the system? Does low power consumption
> justify its inclusion? Would it be better to have the FE machine from
> your main TV act as MBE (the one most likely to be switched on)? I
> tried running the MBE from the Main TV PC and I ran into problems with
> video stutter during peak periods (eg. multiple HD recordings). What
> if the Main TV system was a tunerless MBE? Does a box with HDDs use
> much less than a box with HDDs and Tuners? I know HDDs can be made to
> spin down, do tuners consume much power? Mine seem to get hot so I
> would assume so.

> I think this is a puzzle that will have to wait for 0.22, some
> additional research and some weeks of testing but it is fun to muse
> about. What are your thoughts?

My master backend is always on because it also provides several services
that need to be on all the time (Asterisk for VoIP, web server, mail
server, etc.) This machine has all my tuners. It is headless and it used
to have what I think was a power-hungry nVidia graphics card but even
that is gone now. This machine is a big server, and I wish I could save
more energy with it, but I think I'll have to get new hardware to be
able to do that.

I have two remote frontends that are diskless, and that we suspend to
RAM (using the power button on the remote controls) as soon as we're
done using them. I am hoping that the combination of diskless plus
suspending to RAM will save me a few bucks per year with these machines,
although I don't have any numbers to support anything. I do know that a
couple of months ago I had two machines that were on all the time. Now
it's only one.

Going diskless for frontend machines is something I'd highly recommend.
Besides (hopefully) saving money on energy it is so nice to be able
to maintain a single frontend installation that is shared by several
frontends.

Cheers,

Eloy Paris.-