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acronce
PostPosted: Mon Jan 01, 2007 1:06 pm 
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Posts: 66
I've got a new install of R5E50 on a backend server, with a Mac OS X front end. So far I'm impressed with MythTV in general and KnoppMyth in particular. However I'm seeing some stability problems that are a concern.

The first problem was that the backend froze the other night. I couldn't ping or ssh to the machine. I had to do a hard power down and reboot. I didn't see anything in the logs that stood out. But I'm a myth noob, so maybe I'm not looking in the right place.

The second problem happened this morning. I was moving forward after pausing live tv when the backend went non-responding. I quit and relaunched the remote frontend, but was told that all the tuners were in use. There was no scheduled recording, just me trying to watch live tv.

I happened to be ssh'd into the backend when this problem happened, and I got some disturbing messages in the terminal. Here they are:

Code:
Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: ------------[ cut here ]------------

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: kernel BUG at mm/slab.c:1572!

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: invalid opcode: 0000 [#1]

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: PREEMPT SMP

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: CPU:    0

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: EIP is at kmem_freepages+0xaa/0xc0

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: eax: 8000082c   ebx: c1517080   ecx: fffffffa   edx: 00000000

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: esi: 00000001   edi: c19fc1e0   ebp: e8b84000   esp: f7e1de30

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: ds: 007b   es: 007b   ss: 0068

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: Process kswapd0 (pid: 181, ti=f7e1c000 task=f7e147f0 task.ti=f7e1c000)

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: Stack: c19fc1e0 00000000 e8984000 e8b84000 c01775e0 c19f0260 00000000 c19fc1e0

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel:        c19f5428 c0177724 00000001 0000001b 00000014 c19f53d8 0000001b c19fc1e0

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel:        0000000c c01773c4 00000000 c19f53c0 c19f0284 e89aa278 c19f53c0 00000246

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: Call Trace:

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: Code: 00 00 89 e8 e8 88 87 fe ff f6 87 96 00 00 00 02 74 14 8b 8f 9c 00 00 00 b8 01 00 00 00 d3 e0 90 29 05 10 7d 6f c0 5b 5e 5f 5d c3 <0f> 0b 24 06 6b cd 57 c0 eb a5 8d b6 00 00 00 00 8d bf 00 00 00

Message from syslogd@mythtv at Mon Jan  1 08:41:26 2007 ...
mythtv kernel: EIP: [<c017736a>] kmem_freepages+0xaa/0xc0 SS:ESP 0068:f7e1de30


Seems to be related to memory problems. But I'm totally unfamiliar with the myth source code, so it isn't clear to me what to do with the above info.

I rebooted the machine to get back to a working state.

In case it helps, here's the specs for my deployment:

* Backend:
- Soyo SY-K7V Dragon Plus MOBO
- Athlon 1800+
- 1 GB RAM
- 300 GB Seagate ATA hard drive

* Tuner
- HDHomerun (with both tuners configured)

* Remote frontend:
- Mac OS X MacBook Pro

I really like myth, but can't use it if I have to keep kick starting the backend in the head like this. Thanks in advance for any suggestions.

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Allen Cronce
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tjc
 Post subject:
PostPosted: Mon Jan 01, 2007 1:41 pm 
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Posts: 9551
Location: Arlington, MA
Is the chipset on that Motherboard one of the Via ones? You may want to look into the DMA workarounds for that chipset if it is... Also look for my postings about the "C1 Disconnect" issue.
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acronce
 Post subject:
PostPosted: Mon Jan 01, 2007 3:14 pm 
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Posts: 66
tjc wrote:
Is the chipset on that Motherboard one of the Via ones? You may want to look into the DMA workarounds for that chipset if it is... Also look for my postings about the "C1 Disconnect" issue.


Yes, it is a VIA chipset. Thanks for your pointers. I'll take a look.

Also, I'll consider a different motherboard in the future. This machine is just one that I had laying around. Since this is my first myth installation, I'm considering this a practice run anyway.

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Allen Cronce
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gasheets
 Post subject: HDHomerun and R5E50
PostPosted: Fri Jan 05, 2007 9:09 am 
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Joined: Mon Feb 20, 2006 9:14 pm
Posts: 8
Location: Kansas City
acronce,

I would love to hear a little more about your HDHomerun setup.

Sounds like we have a remarkably similar setup both on the frontend and the backend. I haven't had time to really delve into R5E50 yet, but I hope to this weekend. Are you using the HDHomeRun for OTA on both tuners, or are you using QAM? I haven't investigated if the mythtv .20.1 fixes necessary for QAM with HDHomerun are in there yet. At first scan, it didn't appear that they were.

Thanks,

Tony
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acronce
 Post subject: Re: HDHomerun and R5E50
PostPosted: Fri Jan 05, 2007 10:10 am 
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Posts: 66
Hi Tony,

gasheets wrote:
I would love to hear a little more about your HDHomerun setup.

Sounds like we have a remarkably similar setup both on the frontend and the backend. I haven't had time to really delve into R5E50 yet, but I hope to this weekend. Are you using the HDHomeRun for OTA on both tuners, or are you using QAM? I haven't investigated if the mythtv .20.1 fixes necessary for QAM with HDHomerun are in there yet. At first scan, it didn't appear that they were.


I'm using both tuners for OTA. I don't have cable currently.

I've been very happy with the HDHomerun. Setup was flawless using the silicondust forums instructions. And the few issues I've had with Myth have not been related to the tuners.

My only issue with the HDHomerun is that when I first got the unit, it ran really hot. At rest it was 109 degrees fahrenheit on top and 126 on the bottom. But for some odd reason, the temps have dropped considerably to 99 on top and 107 on the bottom.

Please let me know if you need more information.

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Allen Cronce
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gasheets
 Post subject:
PostPosted: Fri Jan 05, 2007 10:53 am 
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Location: Kansas City
Allen,

2x OTA. Dang, I was afraid you'd say that. I've had a heck of a time trying to get QAM to work on the HDHomerun under KnoppMyth. I updated my last release via SVN (breaking a few things along the way), but was able to get QAM working. It was a small victory, as I pretty much hosed everything else that mattered to me.

I play with it this weekend. I'll report back if I get QAM to work. It was really pretty neat when it worked. I get miserable reception in my area OTA, and only have basic cable.

Thank you for the speedy reply.

Tony
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acronce
 Post subject:
PostPosted: Sun Jan 14, 2007 12:38 pm 
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Posts: 66
After reviewing the forum, I became suspicious that my stability problems are DMA related. Especially since I have no PCI cards installed (I use the HDHomerun for my tuners).

Of course another possible cause of stability problems is bad memory. So I ran memtest 86 from a boot CD. Sure enough, it found a couple of bad addresses.

I've replaced the bad memory and now have a clean bill of health from memtest. Hopefully this resolves the stability problems.

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Allen Cronce
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acronce
 Post subject:
PostPosted: Sat Feb 24, 2007 10:22 am 
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Posts: 66
Since replacing the bad memory, I've had uptime of over 40 days on my backend box. So memory was definitely the problem.

If you're setting up a new system, or if you're seeing any stability problems, I highly recommend running a comprehensive memory diagnostic like memtest86.

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Allen Cronce
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neutron68
PostPosted: Sat Feb 24, 2007 11:32 am 
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Joined: Tue Mar 28, 2006 8:26 pm
Posts: 804
Location: Minneapolis, MN
acronce wrote:
Since replacing the bad memory, I've had uptime of over 40 days on my backend box. So memory was definitely the problem.

If you're setting up a new system, or if you're seeing any stability problems, I highly recommend running a comprehensive memory diagnostic like memtest86.

There is a known bug in R5E50 where the backend stops randomly. Thornsoft wrote a backend-babysitter script which he runs once a minute (as a cron job) to make sure the backend is running and stays running.

See this thread for details:
http://mysettopbox.tv/phpBB2/viewtopic.php?t=13613&highlight=

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KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner
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tjc
 Post subject:
PostPosted: Sat Feb 24, 2007 1:14 pm 
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Location: Arlington, MA
Note that you should disable any such magic restart script during backups and restores. It's a really, really bad idea to have something restarting servers when the backup/restore process has shut them down because it needs the DB in "quiet" state.
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neutron68
PostPosted: Sat Feb 24, 2007 1:27 pm 
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Posts: 804
Location: Minneapolis, MN
tjc wrote:
Note that you should disable any such magic restart script during backups and restores. It's a really, really bad idea to have something restarting servers when the backup/restore process has shut them down because it needs the DB in "quiet" state.

How do we disable a cron job before a backup? Just comment out the line that calls the babysitter script in the /root/crontab.txt file?

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KnoppMyth R5.5, Asus A8N-VM CSM (nvidia 6150 onboard video), AMD Athlon 64 dual-core 4200+, two 1GB sticks DDR 400, HD-3000 HDTV card, PVR-150 card, Iguanaworks RS-232 IR receiver/transmitter, Pioneer DVR-110 DVD burner
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tjc
 Post subject:
PostPosted: Sat Feb 24, 2007 1:33 pm 
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Location: Arlington, MA
I'm not sure cron will automatically reread it. You may need to restart it or signal it to do that.

It might be simpler to temporarily rename the script or replace it with a do nothing dummy.
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