[mythtv-users] NFS and remote backend

[Patrick Ouellette]

On Mon, Jan 14, 2008 at 11:14:27AM -0500, Ryan Steffes wrote:
> 
> The problem, in general, is that the recordings from my OTA HD
> captures stutter slightly during playback, but only while they are
> being recorded.  As soon as the recordings finish, I can watch them
> without trouble.  I'd say this was a network issue, but I can watch a
> /different/ HD recording just fine, just not the one that's currently
> being written to.    The problem grew this weekend, when I reorganized
> my network.    I had been running two combo frontend/backends, and my
> master backend was crammed a little full and got pretty loud and warm
> during recordings.  This weekend, I stuck the recording drives
> (including the DB) and PVR150s into a spare computer and made that the
> master backend and dumped the LVM in favor of multiple storage groups
> to allow the backend to try to optimize disk usage itself.  After I
> got the computers back up and running, I noticed the same stuttering
> problems even on regular streams from 150s.  I changed the option in
> the frontend to "Always stream from backend" (I'm sorry, I can't
> remember the exact option) and the stuttering went away completely on
> low res streams during recordings, but I didn't get a chance to test a
> HD stream during recordings.
> 
> That leads me back to believing it's again a NFS problem of some sort,
> but I don't know what could be causing it.
> 
> Network topology is basically:
> 
> bedroom computer (HD capture card)  -------  1000 link ------   Master
> MythTV   (2x PVR150, Recording partiotions on hda/hdb/sda) ----- 100
> mbs link -----   familyroom computer (Front end only now)
> 
> Bedroom records to mythtv, mythtv records to mythtv, frontend and
> bedroom both playback from mythtv.
> 
> Mounting options are the generic ones recommended in the optimize
> portion of the wiki.
> 
> defaults,bg,actimeo=0,rsize=8192,wsize=8192,nfsvers=3,tcp,soft,intr
> for the 100mbs link, same thing with 32k sizes for the 1gbs link.
> hdparm timings on the drives seem fine (~400 MB/sec cached, ~70 MB/sec
> buffered on all three)
> 
> The fact that it seems like the backend can seemingly stream the video
> with plenty of network space and yet the front end doesn't seem to
> want to read it from the NFS section is what confuses me, and makes me
> wonder if samba could fix the problem.
> 

Are you running two NICs in the master box (one on the gigabit lan and 
one on the 100 mega bit lan) or are you relying on a combination switch
(10/100/1000) to handle the different bit rate conversion?

Pat
-- 

Patrick Ouellette                 pat at flying-gecko.net
kb8pym at arrl.net                   Amateur Radio: KB8PYM 
Living life to a Jimmy Buffett soundtrack
"Crank the amp to 11, this needs more cowbell - and a llama wouldn't hurt either"