[mythtv-users] Some master/slave backend advise required

[Stephen Worthington]

On Mon, 2 Jun 2014 20:59:49 +0200, you wrote:

>Hi,
>
>I’m running myth 0.27 (v0.27.1-7-g41d04b6) on Ubuntu server 14.04 with an i5(3GHz) and 4GB memory. I’m using 4 DVB-S2 tuners as source.
>Due to relocation of the dish I have to install a slave backend. I can’t (don’t want to) move my server to the garden shed.
>
>I have found that recording about 8-10 HD channels simultaneously will start killing processes on the backend (not the myth processes though), but the CPU load of the DVB-s2 stuff by itself requires 100% cpu. Mythcommflagging did not help either, although I could limit the simultaneous jobs to get more breathing space. 
>So my thought was to solve both problems at the same time with a new slave backend, where the dvb-s2 stuff is running, by itself. Storage and commflagging still to be done on the master backend (which has 8TB of ZFS storage)
>
>I can see two issues now:
>Bandwidth: When recording 10 channels (what I want to achieve), I estimate worst case (based on what i recorded so far) 3GB per channel per hour, or 833Mb/s one way traffic, without other overhead. And not watching anything...
>How to solve this, and does myth traffic between master and slave benefit from Jumbo Frames. I could use two network cards in each machine, and create a 2 x1 Gb trunk between the switches.
>Second part of the problem might be that the ZFS file storage is not fast enough. (upgrade to SSD maybe)
>
>Configuration:
>Is it possible to configure mythtv in such a way that it does what I want, or are there better ways to do this? 
>
>Any help appreciated!
>
>Johan

Have you had a look at vtuner (virtual tuners)?  If it works with the
drivers for your DVB-S2 cards, that would allow you to have a minimal
Linux box in your shed with just the real tuners and ethernet in it,
and have the tuners appear as though they were on you main backend
box.

https://code.google.com/p/vtuner/

There are also commercial boxes with builtin tuners that use vtuner.