[mythtv-users] Is there a tuner limit? (problem with >8 tuners)

Chris Wilkie - NetrinoUK chris at netrino.co.uk
Tue Aug 21 18:49:50 UTC 2007

> It has been mentioned a few days back in another thread. You 
> may have done much 
> better, and saved a few questions over bandwidth, if you had 
> done something 
> similar with Myth that you did with the mpeg4 conversions. 
> Namely, twelve 1U 
> boxes, 1 tuner (ok, Nova-T) per box, with it's own disk, each 
> being a slave Myth 
> backend. No contentions there you can't figure out easy.

I appreciate this, however I also have to think about the financial issues.  This is going into a data centre, where rackspace and particularly power are expensive.  Also the cost of the hardware in the first place - even a basic 1U box is likely to be 250, plus the tuner, and use 0.4-0.5A of power (less on a Core2 Duo, but hardware is more expensive).  It will also take up 12U of rackspace, plus a switch, plus another U (and DVB card) for the master backend (for copyright reasons, we have to use the EIT data for scheduling - Radio Times will not licence their data for this use, apparently)

With the DL, I'm consuming ~3A power, and I'm getting 12 tuners into 4U.  It also cost less than a third of what 13 x 1U servers would have done.

> Now the master backend, that's trying to schedule/control 
> that lot, *thats* 
> where you are going to need some beef.

On the current system, with 5 single DVB tuners, we were seeing load averages of 4-5 when all were in use.  That's on a single 2.4 Xeon.
> PS I assume, since you are effectively rebroadcasting stuff 
> over the net, that 
> you have the appropriate permissions from the copyright owners?

Copyright issues are being dealt with by the client - I'm merely building the box to provide the content for them to distribute through their platform.  I know they are gaining/have gained permission for the content that will eventually be distributed, and I know that there are certain restrictions on what can and can't be recorded.  Part of my contract with them passes responsibility to them to ensure any licensing conditions for the material are met.  My setup merely makes the recordings, recodes the material, and passes the finished files back to them.

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