[mythtv-users] Are there any docs that describe the split between mythfrontend and mythbackend?

[Scot L. Harris]

On Fri, 2005-09-16 at 12:37, Dewey Smolka wrote:
> > Thank you for clarifying this.  I don't use MythMusic or MythVideo at
> > this time.  I do use mythgallery so will need to setup NFS for that.
> > 
> > I am also considering setting up NFS for the recordings directory since
> > I have a TB of space on the master backend system.
> > 
> > As I understand this now the NFS for recordings is not required but
> > allows one to keep all the recordings on one system.
> 
> Here is a simplified version of how this works: the backend manages
> tuners and recordings through MySQL. When a FE connects to a BE to
> play live TV or a recording, it streams the picture, meaning the BE
> plays it, the FE displays it. When a FE plays a file through MythVideo
> or MythMusic, the FE does the playing and the displaying, as the file
> is mounted locally as NFS (or just a local directory).
> 
> The recording directory is set up on the BE; The Mythvideo, Music,
> Gallery, etc directories are set up on the FEs.
> 
> Mounting your recordings directory as NFS will allow you to access and
> manipulate the files over a network, but does not affect how those
> files are dealt with in Myth. I imagine that messing around with the
> recordings files over NFS could also screw with the MySQL tables, or
> at least confuse it when it can't find a file where it should be, but
> I don't really know that much about it.
> 
> For example, let's say you've got a bunch of Simpsons episodes that
> you've recorded in MythTV. If the directory is shared as NFS, you can
> access the directory from a remote machine and play the files locally
> without using Myth FE (assuming the local machine can play back the
> .nuvs).
> 
> But if you take some Simpsons that came from somewhere else and tried
> to copy them into the recordings directory with NFS, they won't show
> up in the Play Recordings directory inside of Myth FE, because there's
> no MySQL entry for them (at least that's how I understand it).
> 
> Here's the way I've got my rig set up: a combined FE/BE that sits next
> to the main TV and stores everything on two 250GB drives (with a 20GB
> drive for OS, MythTV and ring buffer). I've also got two remote FEs
> which are full systems (meaning they're also used for non-Myth
> purposes) but which don't have any Myth storage. Each FE has the BE's
> /mnt/media/video (for MythVideo), /mnt/media/music (for MythMusic),
> and /mnt/media/photos directories mounted as NFS.
> 
> It's been a while since I set this all up, but I think I made the
> recordings directory its own partition, which is not NFS since it's
> not necessary.
> 
> The BE will put the recordings wherever you ask it to, but it must be
> a single directory. If your TB of storage is on the BE, there's no
> need for NFS. If your storage is on another machine, you can use NFS
> to have the backend write recordings to a remote volume. But if that
> TB of storage is split across different machines, I don't know of any
> way to use multiple volumes at the same time to store and playback.
> 
> The only other real advantage I could see to making recordings an NFS
> is that you could take the recording out of Myth, edit it or transcode
> or whatever on a different machine, and then put it into MythVideo.
> 
> Anyway, hope this helps.

I think that helped a lot.  Thank you.  

The master backend has four 300GB drives which I have configured to
provide a 1TB /video file system for the recordings.

I am in the process of setting up a slave backend which is where my lack
of knowledge was an issue.  As I currently understand it a slave backend
will store shows it records on its own drives unless the master backend
video drives are mounted via NFS on the slave backend.  

Front end systems based on your description will request the show to be
displayed and will stream that show from which ever backend has that
show.  If I do NFS mount the storage from the master backend I suspect
those shows recorded by the slave backend will get routed through the
salve backend to which ever front end requested such a show.

The database that will be used will reside on the master backend which
will track all of this.

Hopefully that is correct.  :)  

Thanks for the help.