[mythtv-users] Mythbuntu stalling with HDD light solid

[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 use an AMD 780G board with a 1TB Western Digital Green Power EAS HDD 
and a 2.4GHz (or thereabouts) Sempron (Sparta) LE-1200CPU. I have 2 GB 
RAM and have just added an nVidia 8600GT 512MB. I was previously using 
analogue TV over a pvr150 tuner and a bttv tuner. I have just replaced 
the pvr150 and bttv with a Hauppauge hvr-2200.

I have run Mythbuntu for quite a long time. We used 9.10 without too 
much trouble. At some point near the beginning of this year (I don't 
know what triggered it), 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. It is very difficult as the issue causes a whole bunch 
of other issues in the logs (such as buffers filling up or kernel events 
timing out), making it hard to pick the symptoms from the cause. On a 
practical note, stalls during a recording often stop the recording 
taking place, which is pretty unhelpful for a PVR. In top there is often 
a very high percentage of "wa", which I understand means that a lot of 
things are waiting for I/O.

I have now changed the card to an nVidia and am using the proprietary 
drivers. I've replaced 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. 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".

On a few occasions when it has stalled, I have killed mythbackend (sudo 
stop mythtv-backend) and the system continues stalling for another 
couple of minutes. I had decided that the problem could be the hard 
drive itself, because I would get a lot of stalls whenever it was 
accessing the drive (such as when browsing in Firefox or copying files) 
so I tried to copy all of the files from the disk to an eSATA disk. I 
had also heard some rumours about issues with Green Power drives. 
Mythbuntu/Thunar said that this would take 42 hours for 200GB over eSATA 
(and seemed to be taking about that long for the first couple of hours 
or so — it initially said 7ish hours, then I set the ionice to BE7 so 
that it could do a recording, but it went up to 42 and didn't speed up 
after the recording finished), but rebooting to a live CD of Ubuntu 
Lucid Beta 2 did the job in 2 hours. This suggests to me that it isn't 
the disk, but that talking to the disk in Mythbuntu has issues that 
aren't in Ubuntu. I saw stalls in Mythbuntu before I configured it or 
imported my database, which makes me think that it is unlikely a corrupt 
database or similar. I'm struggling to think of anything that is 
different between Mythbuntu and Ubuntu that I haven't tested and 
eliminated as a cause.

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/Mythbuntu-specific or everyone would be 
complaining. I've replaced most of the hardware that I thought could be 
causing the issues.

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

Please note that the issue is very intermittent. Sometimes it does it 
about every 10 mins and sometimes I can watch whole programs (recorded 
or in LiveTV) without it happening.

I couldn't get Mythbuntu Log Grabber to work (it just gives me 
http://mythbuntu.pastebin.com/ ), so I did it manually:
/var/log/syslog:
http://mythbuntu.pastebin.com/wvChWtfQ

/var/log/mythtv/mythbackend.log:
http://mythbuntu.pastebin.com/AdtsnkVT

/var/log/mythtv/mythfrontend.log:
http://mythbuntu.pastebin.com/UUya70RT

/var/log/dmesg:
http://mythbuntu.pastebin.com/jVr1JV5i

lspci:
http://mythbuntu.pastebin.com/ecPJk4Tz

Please let me know if anything else would be helpful.

The most recent stalls that I have recorded were approximately:
9 Apr 06:50
9 Apr 22:10
11 Apr 21:10
12 Apr 20:12

I am also tracking this issue at:
https://answers.launchpad.net/mythbuntu/+question/106466
in the hope that the next person who comes across a similar issue will 
not have to bother everyone.

Thanks in advance,

Aaron