[mythtv] Slave BE, nfs vs cifs vs native proto

gad at jetcom.org gad at jetcom.org
Tue Sep 12 03:13:11 UTC 2006

As we are now in the fall premieres season, and my downstairs tv is  
now dead, I'm using the tv upstairs a lot more..  I have discovered an  
issue with the FE/BE attached to that tv. Playing HD streams ont this  
machine can cause some bad prebuffering pauses when playing off of nfs  
to the master.  Using the myth protocol, it works great. This seems to  
happen when the BE is doing "something", like recording.

The machine is a diskless HDTV FE (A64, 3500+ with DVI out) booting  
off the network. It also is a slave BE for recording stuff off the  
cable box with a PVR150, and for commflagging & xcoding tasks, since  
it's a plenty capable cpu.
The master BE should be plenty powerful, (A64 X2 4200+, 2xhd3000, 1 TB raid 5)
CPUs utilization on both machines are fine.

Since the FE is doing recording, and has no disk, obviously I need to  
write to the master storage via a mount of some sort.  I've tried NFS  
with various options, including 32k sizes, tcp, async.  I haven't used  
CIFS in this configation recently, so i'm not sure of its performance,  
whould it be better?

If i use the myth protocol, it works prefectly, so i was wondering if  
I should make a patch to have a fe configurable item such as  
"PreferNativeProtocol" and use the myth proto for read-only accesses.  
This seems like a straight-forward patch to GetPlaybackUrl. With this  
change I could use the myth proto for playback and commflaggin, while  
i could leave the nfs mount for recording and xcoding.

Does this make sense?  Is there an alternate solution to this problem?
Any other ideas?

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