[mythtv-users] Moving MythTV backend to another computer

[Michael T. Dean]

On 04/02/2014 09:42 AM, Sam Jacobs wrote:
> On 2 April 2014 at 14:23:22, Michael T. Dean wrote:
>> On 04/02/2014 08:51 AM, Sam Jacobs wrote:
>>> On 2 April 2014 at 11:44:11, Michael T. Dean wrote:
>>>> mythmediaserver is for systems that have content (Videos, etc.) to serve
>>>> but no tuners.
>>>>
>>>> And, FWIW, mythjobqueue is for systems that run jobs but have no tuners.
>>> How would one go about setting up a MythTV system that way?
>>>
>>> What about scheduling recordings, editing rules, etc.?
>>>
>>>
>>
>> You still need a master backend somewhere on the network. This is just
>> for the "extra" computers that do things for MythTV but don't have
>> tuners. They needn't be remote backends (and all the tons of extra
>> resources running one requires -
>> http://www.gossamer-threads.com/lists/mythtv/users/365270#365270 ),
>> especially since running a backend without tuners breaks some parts of
>> MythTV.
> Yeah, but the tunerless machine is the only reasonable candidate for the master backend role.

The only way that could be true is if it's because you are trying to 
avoid running cables.  Running 2 backends is actually a waste if you 
don't need them, and I can't think of any reason you'd need more than 
one backend except for scalability reasons--i.e. you have more tuners 
than you can fit/power/... in one backend.  And, anywhere you have a 
backend, you have to have network cables, so in many cases you can use 
network tuners and use the cables you have already run.

 From a power perspective, the remote backend wastes all the power it 
uses when it's on--compared to having the tuners in the always-on PC.  
Even if an idle tuner is using more than negligible power, the 
likelihood that its <non-negligible idle power draw> times 24 hours per 
day is greater than the <whole remote backend system> watts times 
<recording/powered on hours> is very small (unless you barely ever run 
it/record TV).

 From a robustness perspective, it adds additional potential points of 
failure--from failing to wakeup to network failures preventing 
communications with the master backend/mysql server to ...

So why can't you have your master backend have tuners and be the 
always-on PC?

>   Otherwise I’d need to have the PC on simply to schedule a recording, or edit a rule! Or does mythmediaserver also run the scheduler?
>
> I’d really appreciate it if you could point me to something I can use to educate myself as to the specific reasons *why* I shouldn’t have my MythTV system set up the way that I currently do. It doesn’t give me any problems currently, but I’m not using all the features of MythTV and if this setup is going to cause me pain in the future, I’d like to know how.
>

No, as of now, the master backend does all the scheduling and such.  It 
must be a backend.  This is why I recommended just making the always-on 
PC the master backend and sticking tuners in it (or using network tuners 
or ...) or, alternatively, making the master backend system the 
always-on PC.  (So, you could either stick tuners in the current 
always-on PC and run cables for the tuners to it, or you could move the 
current always-on PC to the location with the TV inputs and stick tuners 
in it, or you could move the processes/services that the always-on PC 
provides to the system that's near your TV inputs and make that the 
master backend.)

In the future, we may split the scheduler from the recorders (we will if 
I can convince the others and make the time to finish it).  Until then, 
the scheduling is in mythbackend, and we don't support running a 
"scheduling-only" backend without tuners--so if doing so, problems you 
encounter may well be related to your running in an 
unsupported/untested/known-to-have-some-problems configuration.

Mike