[mythtv-users] Low-power/energy-efficient SD backend/server

John reidjr at lineone.net
Wed May 19 19:35:32 UTC 2010


On 19/05/10 11:14, Vitani wrote:
> Good morning all,
>
> I'm currently using a full-blown 2.8GHz P4 (with HT) for my backend, 
> but it's costing waaay too much to keep that running 24/7 (and it 
> sounds like the inside of an aeroplane in our living room!). I was 
> wondering if anyone here had any recommendations on what I should 
> replace it with?
>
> Things I use the backend for:
> - Recording 1-3 SD programs simultaneously from a PCI Nova T500 (Dual 
> tuner)
> - Sharing those recordings, plus other videos, music & pictures using 
> Samba (my frontends are Xboxes running XBMC)
> - Mythweb & Webmin
> - Transmission torrent client
>
> Things I *don't* do:
> - Transcoding or comm flagging
> - Live TV
> - HDTV
>
> I've done a bit of Googling, but all the site/thread/posts I find are 
> 2 or more years old, and thus are pretty irrelevant (or are they?). 
> I'm happy to build my own box from scratch, or use something pre-built.
>
> Thanks!
> Vitani
>
>
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> mythtv-users at mythtv.org
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>    
I posted this a few weeks back, as you didnt find it in the search, here 
it is again :-)

Travis Tabbal wrote:
>
>
> On Tue, Apr 20, 2010 at 8:39 PM, <glenhawk at optusnet.com.au 
> <mailto:glenhawk at optusnet.com.au>> wrote:
>
>
>     I have been considering the same thing because an "always-on" low
>     power server is attractive. The only major thing holding me back
>     is not being able to install my PCI HDTV cards in it. I have found
>     one ION board with a PCI slot (Zotec I think) and I could put my
>     dual tuner in it and then have a secondary backend for a couple
>     more tuners when needed.
>
Just been round the same loop. I want a silent full speed server that
doesn't use any power :-)

I have a small Buffalo NAS with a couple of 1TB USB drives attached
which is reasonably quiet, and only uses about 10 Watts above the draw
of the Hardrives, so 25W all spinning but idle. Its an arm processor
with 128 M RAM

I have a little acer revo, which is a fantastic machine, dual core,
quiet ( but not silent) reasonably powered with a 160G laptop drive and
1G Ram only 20W all in (about half of a first generation  desktop atom
board)

My old backend had 4 IDE drives with a total of 1TB of storage, a duron
1600 and 3 PCI capture cards, and a total of 115w all spining.

It was all working well wake to record on the backend ( which is
actually probably the lowest power option, depending on the hours the
backend is recording or streaming) But I went through a loop of trying
to run an always-on low power backend.

Options tried:

1) Run  backend on the NAS.  Hard to compile myth on the arm platform,
not enough memory and CPU to run backed, particularly the Mysql
database :-( Possible, but not practical.

2) Backend on the revo. Plenty of CPU for the Job, and memory, x86 so no
compile issues. Using this with the NAS would have been a good solution,
but none of my PCI tuner cards are  useful. DVB-T USB devices are easy
to get, and about 30, got one and it works fine, as long as you are
careful with the chipset you buy ( learned that to my cost)
However two of my tuner cards are dvb-s, and they are not as common or
as cheap in USB versions. There are really cheapUSB DVB-S out there, but
they have no linux support.

3) A hybrid approach, revo master backend with DVB-T, the old backend as
slave with DVB-S PCI cards.
This is a reasonable compromise. If I was only recording TV I would have
probably stopped at this, with wake to record on the slave, so all the
convenience of the always on backend, with the power draw of the revo.
Automatically turning on the bigger machine to record DVB-S channels.
The wake to record fuctions work perfectly in 0.23, with the master
backend closing down and starting the slave. Only downside is I often
use the dvb-s cards for LiveTV, and the wakeup stuff doesnt support it.
In fact it desperately tries to shut down the slave whenever you turn it
on if nothing is scheduled !

You could make this work but I had some of the issues with the hardware.
and moved on to ....

4) Looked again at a stand alone atom board, but we hit the PCI slot
count, a single slot is the most you can hope for. Also as said the
older atom platforms are 40 Watt draw, because of the motherboard chipset.

5) Where I am now ........kind of back where I started.

There is a good article on Toms hardware comparing the power efficiency
of Atom and newer core 2 duos (both 45nm fabrication). Not that much in
it really

Replaced the old motherboard with a cheap Gigabyte 775 board, with a low
end 45nm core2duo chip. I also swapped things around to make sure I had
a good 80+ powersupply.

Changing the power supply saved about 10W, which is surprising, ditched
some of the smaller drives, 7 watts each, and the dvb-t pci card 7 watts.
Gigabyte GA-G31M-ES2L iG31 Socket 775
So my backend is now 2 hardrives, 2 DVB-S PCI, 1 USB DVB-T, 80+ PSU, a
Gigabyte GA-G31M-ES2L iG31 Socket 775 and an e3300 cpu. The gigabyte
board lets you undervolt the processor, and if you let everything but
the boot drive spin down, it idles around 50W at the wall. So not much
more power than  a cheaper atom board, with only about 40W being used by
the MB/processor and psu losses. The rest is the DVB-s cards and HD when
spinning. The up side is for a few watts more at idle, it has the guts
to do other things if needs be. It leaves me with 4 spare SATA ports, a
2.5GHz dual core CPU and 2GB ram for emergencies or other applications
to use.

Hopefully the info on pros and cons will be useful, even if you don't
end up with the same conclusion.

john
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