[mythtv-users] Disk utilization on slave backend questions

Chad masterclc at gmail.com
Sat Jul 9 16:49:31 EDT 2005

> Correct. Playback can go over a socket between a backend and
> frontend but there is no socket for one backend to send data
> to another backend to write the file (nor should there be).
> Mythbackend just needs a path to a writable directory.
> > In other words, the master backend knows how to get data from the
> > slave backend without requiring NFS.
> Master and slaves don't actually send recording data file content
> between each other. It is when a frontend wants to do playback
> that the magic happens. Say you have master "A" slave "B" and
> slave "C" each with local disks. You sit at host "C" watching
> the frontend and you select a show that happens to have been
> recorded on "B". The frontend asks the master 'hey, where can
> I find this file?' The master says it is on "B". The frontend
> on C then opens a socket to the backend on B who starts sending
> the data. These two myth processes negotiate a "read ahead buffer"
> that sends data ASAP while playback is going on until it gets
> two MB ahead.
> Next let's say you pick a show that was recorded on "C". You
> would think it would go through the same steps again to connect
> to the local backend. However, the frontend cheats. It first looks
> to see if there is a prefix directory setting for it's hostname.
> If so, it checks to see if the file is there and will open the
> local file without going through any backend (this is a good thing).
> Because the frontend can read a local file or do smart application
> specific buffering for remote files, you don't need NFS for
> playback.
> --  bjm
> _______________________________________________

Wow, nice explaination!

I just wanted to chime in and say that one does need NFS mounts IF
they are using mythvideo/mythmusic.  I chose a central location for
these files, and they are a subdir of my existing MythTV recordings
directory, which is universally /mnt/MythTV.  So, on my MBE I create a
directory /mnt/MythTV/videos and NFS export ONLY this directory to the
frontends.  That way the recordings are still held locally in
/mnt/MythTV, but the NFS mount directory /mnt/MythTV/videos is


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