[mythtv-users] large mythtv deployment

[Josh White]

On Sat, Nov 15, 2008 at 2:38 PM, Michael T. Dean <mtdean at thirdcontact.com>wrote:

> On 11/15/2008 02:05 PM, Michael Johnson wrote:
> > On Sat, Nov 15, 2008 at 12:55 PM, Michael T. Dean wrote:
> >
> >> On 11/15/2008 11:40 AM, Michael Johnson wrote:
> >>
> >>>  On Sat, Nov 15, 2008 at 10:29 AM, Mike Perkins wrote:
> >>>
> >>>> Michael Johnson wrote:
> >>>>
> >>>>> I am doing a fairly large deployment of mythtv at work and I am
> >>>>> looking for any pointers that may help us out. So far we have the
> >>>>> following hardware for a mythtv cluster and we are now debating
> >>>>> over the hd5500 or the WinTV-HD capture cards. We want 8x
> >>>>> backends and 8x frontends.
> >>>>>
> >>>> Why on earth do you want to have eight backends? Are you setting
> >>>> these up to be completely independant of each other? It's not
> >>>> necessary, and you will be duplicating files and effort.
> >>>>
> >>>  We have 8 satellite feeds. So we don't necessarily want 8 backends,
> >>>  however we want 8 capture cards hooked up (somehow) to the hardware
> >>>  we have below.
> >>>
> >> Are you sure that will work?  Are you absolutely certain that you're
> >> getting ATSC feeds from your satellite?  And, if so, are you absolutely
> >> certain that these feeds are unencrypted?  If the answer to either
> >> question is no, the HD-5500 (and likely--though I don't know the
> >> hardware--the WinTV-HD) won't work at all.  Feel free to ignore me since
> >> it sounds like you have some special setup, so you probably know what
> >> you're doing, but I just thought I would mention it just in case.
> > when I say satellite feed I mean we have 8 satellite receivers in a
> single
> > room and we plan on controlling them with an ir blaster.
>
> Wouldn't that mean your only real option is the Hauppauge HD-PVR?  The
> HD-5500 needs an unencrypted ATSC source (i.e. Over-The-Air broadcast
> (8VSB modulation) or unencrypted cable (QAM modulation)).
>
> You cannot input Component/VGA/DVI/HDMI to an HD-5500.  TTBOMK, the only
> thing you can use with Myth that takes an uncompressed HDTV signal (via
> Component) is the HD-PVR.
>
> Still, though, the HD-PVR does all the compression for you, so the
> backend would just be writing data to disk.  If you run commercial
> flagging, the backend would also do that (though you can run
> mythjobqueue on any machine--including a very powerful frontend--to run
> commflagging jobs).  And, as Steve mentioned, transcoding is also
> normally done by backends (but can be done by any mythjobqueue host, if
> it has "local" access to the file--even using NFS or CIFS).
>
> Mike
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>

If you're going to have all your frontends and backends in the same room,
why not use the dual/quad core machines you have as both frontends and
backends?  From what I understand, the only reason to use a separate
frontend and backend is due the load incurred by the tuner cards.  Most
people don't want a loud, hot, large computer case in their livingroom, and
therefore they build a backend to contain all the messy stuff, put it in a
closet/garage/basement/etc. and put a more presentable machine near their
display as a frontend.  If you're going to put all these machines in the
same place anyway, then there's little reason I can see to not to use them
as both frontend/backend machines (assuming I/O isn't a problem).  From the
hardware you describe, you should have plenty of computer to do both with
any of your machines.  If I were working on this, I would probably use the
dual/quad core machines to handle it all, and then you should be able to
reserve at least one cpu core per machine for commercial flagging, and at
least one per machine for displaying the content.  Assuming your machines
have at least 2 PCI slots/motherboard, that should allow you to use 8 single
tuner cards, and each machine should have plenty of USB ports to handle the
remote and ir blaster.  That way, instead of running 12 power supplies,
you're only running 4 (though if you plan to heat the facility with the
waste heat from the myth system, then maybe this isn't a benefit).  Perhaps
using one or two of the P4's to house a raid array would make sense; if you
were to have a large video collection in addition to the recordings you
intend to create.

That's my $.02, good luck; it sounds like you have an interesting project on
your hands.

-Josh
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