[mythtv-users] New install - Backend, multiple frontends - re ccomendations

[Jim Moseby]

> 
> On Aug 25, 2006, at 10.12, Jim Moseby wrote:
> 
> > Hi all,
> >
> > I'm new to the group, and to MythTV.  I am excited about the  
> > possibilities,
> > but have some basic questions.
> >
> > I am in the process of building a house, and I am almost at the  
> > point where
> > I am installing media and network systems.  My plan is to 
> install a  
> > single
> > backend server with, say, 6 TV cards in it, and put little 
> diskless/ 
> > fanless
> > frontend boxes at each TV location (4 bedrooms, Family room,  
> > kitchen, and
> > office).
> 
> Wow. That sounds like quite a load for one box. Can you imagine  
> commercial flagging several recordings simultaneously? And I'm not  
> sure how lucky you're going to be, finding a box with six PCI slots.  
> That is, unless, you're going SD, in which case you might not be so  
> bad off with three PVR-500s (but that's still quite a load)

Thanks for the quick reply.  The PVR-500 seems to be a popular choice I've
seen in the few days since I've discovered MythTV.  HD is a 'want', not a
'need' so I'll opt for these.  On eBay, I'm seeing these new for ~$135,
pretty reasonable.  I notice they take up two slots (one for the card, one
for the secondary connectors.  Will I need the secondary connectors in this
application?  Can I just remove them from the card?


> 
> > Having never done this, or even seen MythTV in action, I 
> have a TON of
> > questions.  I have read the documentation, and still several  
> > questions have
> > arisen.
> 
> My advice: start small. Try a single box set-up, then move on to  
> adding front-ends.

That's sound advice, and I will definately take it. To set up a single box
before investing a lot of time and money into this is the definately sane
approach.  I assume I can go ahead and buy a single PVR-500 to install into
my server, and test it there.  Is adding a frontend to a single box setup a
simple process?  Is adding additional tuners after install a simple process?

> > First, hardware for the backend.  My plan is to use cards that do  
> > hardware
> > encoding, because the docs say that will relieve the CPU 
> from a large
> > portion of the work.  I have access to a Compaq quad zeon 1Ghz  
> > server with a
> > terabyte of SCSI RAID storage in pluggable drives that I hope to  
> > use.  I
> > would like this to serve as a single backend system, running the  
> > database,
> > storage and HDTV cards.  Sufficient?  Would you split out the  
> > backend duties
> > to multiple servers? (Recommendations as to which HDTV cards are  
> > most stable
> > and supported would be great.)
> 
> I'd farm out with multiple back-ends. I use a single Celeron 
> 600 with  
> a single SD capture, and even then, sometimes I'll have a 
> show before  
> it's been commflag'd. Plus there's the sheer number PCI slots you're  
> going to need. A Quad 1 GHz Xeon might do a good job, though. 
> I don't  
> have enough experience to speak on that as far as processing 
> power goes.

I don't know either.  The documentation says "A PIII/800MHz system with
512MB RAM can encode one video stream using the RTjpeg codec with 480x480
capture resolution and play it back simultaneously, thereby allowing live TV
watching."  I take this to mean that a quad 1Ghz Xeon with 2G of ram would
theoretically be able to do 4 such operations simultaneously. (?)  That
assumes MythTV can take full advantage of a multi-processor box.  My
fallback plan is to use the Xeon box for database and storage, and put in a
couple of additional boxes for the tuners if I absolutely have to.

> 
> > I'm thinking the hardware for frontend systems will be 
> based around  
> > the tiny
> > VIA EPIA motherboard.  With those, I can build little netboot  
> > systems with
> > no moving parts.  There will be 7 of those total.  Sufficient?
> 
> I've heard good things about those, but it depends on which mobo you  
> go with, to make sure you get enough oomph to do HD. Plus, you'll  
> have to set up the UniChrome Pro stuff to get XvMC to work.

Definately.  I've read good things about them too.

> 
> > The network to support it all will be Gigabit at the backend, and  
> > 100M to
> > the frontends, switched with a Dell PowerConnect 2124 switch.  I  
> > could find
> > no documentation about the network requirements for a 
> backend/frontend
> > setup.  Will this be sufficient?
> 
> I tried streaming SD over a 10M line. It wasn't pleasant. If you can  
> go 10G for the back-end, I'd (personally) feel a bit safer. 
> But, then  
> again, I've never dealt with HD.

I figure I have 7 100M devices hitting a server on a 1G backbone.  So each
of the 7 devices can pull a full 100M stream while still only saturating the
1G backbone to 70%. Assuming the switch can buffer that fast, there should
be no bottleneck.

The question then becomes, "...is 100M sufficient for a frontend system?".
I believe it is for SD, as I have read in the list archives of people having
good results over 54M 802.11g wireless. (Other than the periodic
disconnect/reconnect they tend to do).

> > My hope is that we can have all 7 stations either watching 
> live TV,  
> > playing
> > MAME games, listening to music or whatever simultaneously with no
> > degradation of performance or quality.  Any input from the group  
> > towards
> > this end will be much appreciated.
> 
> Good luck with this.

Thanks, I'll need it.  ;-)  (..and I appreciate your response.)

Jim