[mythtv-users] slave backend using NFS for ringbuf

Chris Pinkham cpinkham at bc2va.org
Thu Jan 24 18:43:54 UTC 2008


* On Thu Jan 24, 2008 at 10:43:24AM -0600, Gerald Brandt wrote:
> I just set up a slave backend, and I use NFS to mount the myth shares from the master backend. This means that the slave uses the NFS share for it's ringbuffer. 

> Is this a good thing to do? Is there a way around this without throwing massive hard drives into the slave? 

It's fine, my master has no local storage and neither does my first slave.
They both use a common NFS server.

> The reason I'm asking is my frontend keeps getting errors: 
> 
> 2008-01-24 10:46:47.474 NVP: prebuffering pause 
> 2008-01-24 10:46:47.661 RingBuf(/mnt/raid5/myth/tv/2981_20080124103351.mpg): Waited 1.0 seconds for data to become available... 
> 2008-01-24 10:46:47.661 Checking to see if there's a new livetv program to switch to.. 
> 2008-01-24 10:46:48.711 RingBuf(/mnt/raid5/myth/tv/2981_20080124103351.mpg): Waited 2.0 seconds for data to become available... 
> 2008-01-24 10:46:48.711 Checking to see if there's a new livetv program to switch to.. 
> 2008-01-24 10:46:48.971 NVP: Prebuffer wait timed out 10 times. 

These may be due to attribute caching.  The frontend isn't seeing the file
soon enough.

Check out the NFS client tuning options on this page:

http://www.mythtv.org/wiki/index.php/Optimizing_Performance#NFS_servers

The actimeo=0 is the one that may solve your issue.

> On another note, is there a way I can make a frontend prefer a specific backend? 

No, the frontends always talk to the master backend directly, then if they are
watching LiveTV from a slave, they may stream directly from the slave unless
they can see the recording files directly or if the Master Backend Override
setting is on in which case the frontend would stream from the master before
streaming from the slave.

--
Chris


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