[mythtv-users] How to force frontends to play only from master backend?

[Michael T. Dean]

On 03/15/2009 05:08 PM, Nick Rout wrote:
> On Mon, Mar 16, 2009 at 9:42 AM, William <william_munson at comcast.net> wrote:
>   
>> Harry Coin wrote:
>>     
>>> Using 0.21 I need help to cause frontends to play from the 'masterbackend'
>>> only, even though diskless other slave backends that received and stored the
>>> shows are running on the same little net.
>>>
>>> I have some older, slower diskless PC's acting as slave backends.  These
>>> were just supposed to catch the video and put it on the common nfs share,
>>> never host playbacks.   There is a master backend that has an NFS share that
>>> all the frontends and backends can access.  The masterbackend is fast, has
>>> quick disks and has a fast network connection.
>>>
>>> But, I've proven that the frontends actually don't actually pull from the
>>> master backend either stream or nfs, but contact the slave backend that
>>> recorded the video, cause that little underpowered thing to pull the video
>>> from the nfs share, then stream it out to the frontend.    So, bad
>>> performance, choppy playback, dropped frames on recording and so on.
>>>
>>> So, I really need to turn off any kind of playback activity / streaming
>>> from all the diskless slave backends - but to have them still be running to
>>> host the tuner cards and record shows.   Help please!
>>>
>>> Last, I'd appreciate some guidance about whether the frontends would do
>>> better to use NFS to playback from the server, or cause the server to stream
>>> -- and tell me how to direct the frontends to implement that decision.
>>>       
>> There is an option to always stream from the backend with a check box on one
>> of the setup screens, Sorry but I am not able to get to the system right now
>> to give the specifics
>>
>> I think its in mythtv-setup rather than the frontend setup.
>>     
> I think its in frontend setup as I just noticed it when setting up a
> new frontend yesterday.
>
> However I am not sure that it achieves the aim of "always stream from
> the MASTER backend rather than the backend that recorded it"

Right, Nick.  The mythfrontend setting is:

Always stream recordings from the backend
Enable this setting if you want MythTV to always stream files from a 
remote backend instead of directly reading a recording file if it is 
accessible locally.

and it makes the recording host stream the show.

There's also the mythtv-setup setting:

Master Backend Override
If enabled, the master backend will stream and delete files if it finds 
them in the video directory. Useful if you are using a central storage 
location, like a NFS share, and your slave backend isn't running.

but that would only make the master backend stream the files if you 
shutdown the recording host.

However, if you have a "local" copy of the file available to the 
frontend--i.e. a copy of the file on a filesystem that's directly 
accessible by the frontend (which means NFS mounts are "local")--the 
frontend will read the file directly from the disk (which would mean 
from NFS).

In your test, it didn't do so because you either had enabled the 
setting, "Always stream recordings from the backend", or your filesystem 
is using a different structure on the frontend from the backend(s).  So, 
uncheck that option and/or make the directory structure of the recording 
directories /exactly/ identical on /all/ hosts (backends and frontends), 
and all will work.

Mike