[mythtvnz] System freezes thrashing HDD

[Aaron Whitehouse]

Hello all,

I've spent a long time trying to narrow this down, but I'm really 
struggling and could do with any help/suggestions that you can come up with.

I have run Mythbuntu for quite a long time. We used 9.10 without too 
much trouble. After some updates near the beginning of this year, 
Mythbuntu started stalling for 1-3 minutes at a time, with the hard disk 
light on solidly and nothing else working. The system would be virtually 
unresponsive, but would slowly crawl to a terminal etc. Then, after 
about 1-3 mins, it would be back to normal. I can't see anything that 
could be causing the problem in top, iotop or the system logs. There are 
some entries in the logs about different kernel tasks being killed 
because they didn't start properly in 120 seconds, but I think that is a 
symptom rather than a cause.

I have now changed the card to an nVidia and am using the proprietary 
drivers. I've removed one of the tuner cards. I upgraded the system to 
Lucid Beta and downloaded all the latest updates. The problem is still 
occurring, even when all I was doing was browsing folders in Thunar, so 
that suggests to me that it isn't MythTV causing this (mythbackend is 
still running, but I haven't loaded in the database or set anything up). 
To give an idea of the problem, running a 42 minute video in VLC took 53 
mins with the stalls.  The memory looks okay (I have 2GB in it), with 
free -m showing most "used", but "cached".

I haven't yet sorted out all of the VDPAU etc., but I'm guessing that 
those are unlikely to solve the problem when it stalls the system so 
much that even a terminal can't work.  Given that it isn't showing in 
top/iotop, I'm wondering if it is something really low-level. On the 
other hand, I would have thought it would need to be hardware-specific 
or everyone would be complaining.

If anyone can help me, it would make a huge difference -- even if only 
to suggest more diagnostics or logs to review.

Thanks in advance,

Aaron