[mythtv-users] 0.17 backend issue - playback erratic

[Troy Roberts]

I have been having problems with playback of recorded shows since 
upgrading to 0.17.  The video will freeze for a second or 2 repeatedly 
for a few minutes.

The setup:

Backend with 3x PVR250
P4 2.8Ghz, 1GB Ram
2x SATA Seagate Barracuda 300GB disk
The ringbuffer, music, videos, database, are all on one drive, recorded 
TV is on the other
No frontend on the backend server
The backend is connected to gigabit ethernet switch

2x frontends - no capture on the frontends
frontends are connected via 100Mb FDX
P4 2.x Ghz with 512MB RAM
nvidia FX5200 video cards

All systems are running debian unstable with 2.6.9 kernels

 From what I can tell so far the problem appears to be some sort of 
blocking problem on the backend - I have noticed that sometimes when 
this occurs mythcommflag is running on the backend, but can't say that 
it is for sure all the time.  The recordings themselves are fine, as I 
can stop the playback, and return to it sometime later, and all is fine.

I am inclined to think this is not a frontend issue, because I can 
playback the shows later with no issues.  I have looked through all of 
the relevant logs, and the only thing I see that arouses suspicion is 
the backend log has a number of IOBOUND messages in it from time to time.

The IOBOUND error seems odd to me for a few reasons:

1) the hardware part of this setup has not changed since 0.16 and I 
*never* had this problem with 0.16 - I am not recording any more or less 
streams now then I was on 0.16 - once I upgraded to 0.17 this started to 
show up right away

2) I can't imagine that there is nearly enough data moving around to 
saturate the SATA bus

3) I see no other evidence of io issues from any other logs, subsystems, 
etc on the system

Any thoughts would be appreciated,
Troy