[mythtv-users] Multiple Frontends / Backends

Bruce Markey bjm at lvcm.com
Thu Jul 1 14:43:00 EDT 2004

John Goerzen wrote:
> Yes, I'd like to keep all the files in the same place.  I gather that it
> is permissible to mount the "main" storage area on the slave backend,
> and thus share the exact same directories with the master.
> Now, let's say something like this happens:
> 1. Slave records a program, stores it in NFS.
> 2. Slave then is turned off/goes down/whatever.
> 3. Files are on master but slave is unreachable.
> Will I be able to watch the recorded programs still?

Yes. The hostname of the recording machine is stored in the
database so that the frontend can be told which machine to
connect to for playback. However, if the file is found in the
local file directory path (because of NFS in this case) it
would go ahead and open the local file regardless of the
hostname. This is done for efficiency because it is better for
the frontend to read a local file directly than to ask a
backend to stream the data so it always looks at the local
path first.

> How about this:
> 1. Slave records a program, stores it using NFS to master.
> 2. mythfrontend is run on master machine, recorded program is played.
> Will the master's mythfrontend attempt to stream the program from the
> slave?  If so, the slave in that case would be reading it via NFS from
> the master.  Content that is then local to the master's mythfrontend
> would be sent across the network twice.  Does Myth have some mechanism
> to prevent that problem?

See above =).

> Is it required to have a mythbackend on a machine that runs mythfrondend
> and has no capture cards?

It is not required to have a mythbackend on a machine that runs
mythfrondend and has no capture cards. If there are no capture
cards then no mythbackend. A frontend only needs to connect to
the correct mysql server which in turn tells it where to find the
master backend.

[Another reply may have been crossed up by multiple issues and
implies differently, however, the answer to the question is an
emphatic NO.]

>   I couldn't figure out how to make
> mythfrontend talk to a different backend server, especially since
> mythtv-setup is part of the backend package (!).

As before, mythtv-setup shouldn't be in the picture here. For
frontend only you need; mysql.txt to point to the one and only
mysql server, network access to that server, the real IP address
of the one master server in the database. If this is correct the
frontend will talk to the master and can playback files from
the master or any slave.

The frontend always connects to the master first. If you ask to
playback a recording that resides on a slave, the master will
tell the frontend where to connect to get that file. The frontend
then opens a connection to that slave and the slave begins
streaming the file.

--  bjm

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