[mythtv-users] Power efficient backend-only server

Richard Morton richard.e.morton at gmail.com
Tue Oct 20 11:53:01 UTC 2009


Be careful with drive spindown especially on 2.5" drives. They're not built
to take the potentially regular and long term on/off abuse and they die
quickly in my experience.

A drive takes twice the current during spin up as it does just running; on
spin down they cool down as well and this te,perature change cycle has been
shown to cut drive life significantly.

Don't believe the hype, saving power at the expense of life expectancy of
the drive is NOT environmentally friendly or cost efficient

R

Please excuse brevity and mistakes, this email was composed on a mobile
phone.

Thanks and regards,
Richard Morton
07899750400



On Oct 20, 2009 12:44 PM, "Greg Cope" <gregcope at gmail.com> wrote:

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...
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