[mythtv-users] Power efficient backend-only server

[Greg Cope]

Hi,

If you are running DVB Nova-T's I assume you are not doing Commerical
skipping or transcoding.

IF the above is correct, you need sod all processing power, just
enough to cope with the IO (network or otherwise).

Any atom based board/system would work fine (20w ish) (think nettop).
Or a via based board (I use an SP13000 as a front/backend).

To get a little over the top you will notice that the thermal (and
hence power requirements) of systems these days are as much driven by
their system board chip sets as the CPU - ie early atom boards had a
low power cpu (5w?) combined with a heater, sorry, chip set that
struggled to draw less than 15W.

You can aim to get the board+disk to consume around 30W (20W for the
system+cpu, 5w for each of disk+Nova-T YMMY).

Thus do NAS'es - I believe (But could be wrong) that all the small
NAS'es run linux or freebsd underneath.  Although you will find it
hard to find, you need to be carefully about the power draw of a
NAS/always on thingy - see below for my USB/ESATA enclosure power
draw.

To give you a benchmark my FEBE draws 60W and includes;

SP13000 board+CPU
2xNova-T PCI cards
2x400 SATA drives
1x750 GB PATA drive

Sadly the age of the chip set/OS release means it cannot do drive spin
down as that would save another 15w average.

I am planning a replacement with a Acer Revo (20w-30W), USB twin Tuner
dongle (5w?), and a 1.5TB ESATA drive (5-7w).  This should drop to
around 40W, less at idle.  Presently strugging to get my ESATA
enclosure to draw less than 7w when the drive inside (1.5TB Samy green
power) should only be drawing 4W (ie the transformer/chipset
efficiency is rubbish at nearly 50%).

Why am I so anal about this?  Simple - dropping 20W of continuous draw
saves around £20 a year (at present prices), or £80 over a 4 year
life.  Also lower power means low heat, low noise,  and hopefully
better reliability (due to less heat issues).

Greg

2009/10/20 Vitani <vitani-mythtv at tfxsoft.com>:
> Good morning all,
>
> I currently have an old desktop PC running Mythbuntu (backend-only), using a
> Nova-T 500, but it's big, loud, and relatively expensive to run. I was
> thinking about getting a mini-itx motherboard (or smaller!), which used a
> laptop hard drive, all in a nice small case, and pair that with a
> Linux-based* commercial NAS (so should the MythBox die I can still access my
> other media). That's the plan, but I'm not sure how much processing power a
> backend-only system would need. There seems to be a lot of articles on the
> Wiki about hardware, but most are out of date (they talk about version 20),
> and/or focus on front-ends or both-end set-ups.
>
> I had a look on the PVR Hardware Database and only one entry really seemed
> to fit what I was looking for -
> http://pvrhw.goldfish.org/tiki-view_pvrent.php?systemid=Myth%20BackEnd%20Only
> - but that set-up used a 2GHz Pentium 4, which I obviously would not be able
> to run on my planned system.
>
> So my question is, has anyone created a backend-only MythTV system using a
> small, power efficient computer, and if so, what components did you use, and
> how well does it run?
>
> PS. If anyone knows of any commercial NASs which do run Linux, could you let
> me know, as I've not found one yet.
>
> * the NAS doesn't have to run Linux, but I'd like to be able to set up
> symbolic links from the NAS to the MythBox in order to access the recordings
> directly over Samba.
>
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