[Solved] Video Playback Freezes Except When Dashboard Is Up


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I have a particularly vexing problem.  I have a media library on an 8 disk unRaid server.  When I playback video (generally H.264 1080p MKV files) on a Kodi client or Plex server over the network (using SMB), I often get playback freezes.

 

I ran the unRaid dashboard through a web browser on another computer on my network to check memory and CPU utilization.  The CPU usage briefly shows very high (as much as 100%), then drops down and stays down.  As long as I have that dashboard running on a web browser, my playback freezes go away.    If I close the web browser, the freezes start again.

 

I've checked the log (attached below), and I don't find any error messages.

 

My system is a Celeron 420 CPU with 2GB RAM.  9x Seagate 4TB Drives (8 + Parity; no cache).  XFS file system.  unRaid v6.3.5.  Hardwired Gigabit Ethernet network connections.  No unRaid plugins.  Nothing else running on the system.

 

Any thoughts on what to do here?  If not, is there some sort of utility that will do the same thing as keeping my UnRaid dashboard up in a web browser?

 

Thanks so much for your help!

 

Best

BB

bbmedia-diagnostics-20170807-1957.zip

Edited by bb80301
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OK, I looked through your logs, Smart reports and network settings.  I saw nothing that would even indicate any type of problem.

 

Then I looked up your CPU and found the Passmark CPU benchmark for your CPU.  It was 452.  With that figure in mind, let me tell you a little story.  More than two years ago, back in the days when version 6 was in beta, I was running a AMD sempron 140 with a Passmark CPU benchmark of 738.  I was also having problems with playback freezes (actually more stuttering than as actual freeze) only on playback of 1080 material.  In my case, it was BluRay iso rips.  

 

Since version 6 was in a beta testing phase, LimeTech and I ran a whole series of tests.  We determined that the problem was with the RealTek NIC chip set and some type of interaction between its driver and the Linux kernel.  (You have a RealTek NIC on your MB-- I can tell because I found the RealTek driver being loaded in the syslog.)  Apparently, the problem only crops up with low end CPU's with limited CPU processing power.  And your CPU only has about 60% of the processing power of my old AMD CPU.

 

What the resolution to my problem was the use of an Intel network card.  You can use either a PCI-E (~$26 on Amazon) or a PCI (~$20) card to use.  (Look at your MB and see what slots you have available before ordering.  Chose a vendor with a liberal return policy in case things still don't work right.)  That fixed the problem for me and a couple of other folks who ran into this same problem.   Of course, you could also do what I eventually did and that was to replace both of my Sempron MB's(late last year)  with what you see in my signature.  I hope this helps...

 

PS--- I would recommend the PCI-E card because one of these days the PCI slot(s) may just disappear from MB's...

Edited by Frank1940
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Thanks so much for your comprehensive answer, Frank.  Much appreciated.

 

If I replace the motherboard-based NIC with a network card, will I need to somehow disable the RealTek NIC?

 

Also, if anyone has any ideas why the problem goes away when the dashboard is active, I'd be very interested.  It's very odd, but it's happening.

 

Thanks, again!

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25 minutes ago, bb80301 said:

f I replace the motherboard-based NIC with a network card, will I need to somehow disable the RealTek NIC?

 

 

Yes and you do it in the BIOS.  (Someone may jump in and say you don't need to that but the setup will be simpler with it.  Plus, having two active NIC's is going to put more work onto an what is already an underpowered CPU for modern applications.  Using only the Intel network card will actually reduce the workload on the CPU as the card has the 'smarts' to handle much of the handshaking with the network instead of the CPU having to do it.)

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47 minutes ago, bb80301 said:

Also, if anyone has any ideas why the problem goes away when the dashboard is active, I'd be very interested.  It's very odd, but it's happening.

 

 

The issue cropped up when they incorporated the preemptive kernel into the unRAID.  This was made necessary to solve some other issues (BIG ones) with Dockers and VM's.  It solved those problems but it did generate a (very) few new ones including this one.  Apparently, It has only impacted a few people and most of them solved it with the Intel card.  There was an short investigation into seeing if there was some root cause of the problem but no smoking gun was ever found.  (You can also 'fix' it by never streaming 1080 video...  9_9  )

Edited by Frank1940
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@Frank1940 any suggestions on which Intel Card to pickup or to avoid? I'm looking at PCI versions myself. 

That is if you have any particular suggestions. :) Otherwise I'll just grab a Intel 1000mbs PCI and roll the dice myself. 

 

I bring this up because I had a Sempron 140 and ran it on a BioStar Mobo aka one of the Original Budget Builds. I've moved on past the Sempron, but sometimes suffer with some lagginess that I seem to get for some odd reason. 

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2 hours ago, kizer said:

any suggestions on which Intel Card to pickup or to avoid? I'm looking at PCI versions myself. 

That is if you have any particular suggestions. :) Otherwise I'll just grab a Intel 1000mbs PCI and roll the dice myself. 

 

I purchased (back in 2015) two of the same cards as @bb80301 has ordered.  The comment that I made in a previous post still applies.  You should be looking at the slots that you have open on your MB and think about any future expansion that you may want to do with this system.  If it is tossup as to which one to use, I would go with the PCI-E card.  The reason is that PCI slots will probably completely disappear in the next few years.  With a PCI-E card, you will be able to use it in any new build in the next ten years.  You may wonder why you would want to do this. MB with only one NIC on the MB are cheaper than ones with two or more.  However, in the future, unRAID may have increased capability to use two or more network ports.  With the PCI-E card, you could use the less expensive MB and recycle the Network card as a second Network interface device.  Another plus would be that it would be much easier to resell if you decide that you no longer have a use for it. 

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Thanks guys. I'll check out how much space I have in my machine Just depends on how much space I have next to my Sata Controller. My New to me machine already has a Intel Nic built in, but I suppose if it was flaking out I could throw in a PCI-E from this just as well. 

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15 minutes ago, kizer said:

Thanks guys. I'll check out how much space I have in my machine Just depends on how much space I have next to my Sata Controller. My New to me machine already has a Intel Nic built in, but I suppose if it was flaking out I could throw in a PCI-E from this just as well. 

 

Are you having some playback issues or is this something else?  After using the Intel Network cards to fix the playback problems, I tried upgrading from the Sempron 140 to one of the multicore AMD processors and found that it didn't do much for the issue that I was having at that time (dual parity check speeds).  In my own mind, I came to the conclusion that the addition cores of AMD chips were not being used efficiently by the Linux kernel.  That is one of the reason that I made the switch from AMD to Intel beginning late last year. 

Edited by Frank1940
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Play back seems fine when I'm using Kodi, but if i use Plex on a Desktop machine it seems to act a bit odd. Basically its a slight but noticeable shutter every 15 or 20minutes. Not sure if its a Transcode and stream at the same time or if its network related. I'll do some testing or just give in and deploy my new machine. Lol I was hoping to squeeze some more juice out of my machine, but I guess you can only squeeze a rock so hard before it doesn't produce anymore. xD

 

I'm probably going to say its probably a Transcode and stream issue if its taking HD and Transcoding it down to 2CH from 5CH on the fly. 

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3 minutes ago, kizer said:

I'm probably going to say its probably a Transcode and stream issue if its taking HD and Transcoding it down to 2CH from 5CH on the fly. 

 

I really don't think that CPU has the horsepower to transcode even audio using plex while streaming 1080p.  It only has a Passmark rating of about 800 per core and, in my opinion, that whole family of processors don't perform well with modern OS's that expect multi-threading efficiencies from the CPU.  I would not expect the Intel netwrok card to have any impact on this situation.  If it is really a big issue to you, you might want to explore upgrading the MB and CPU.  There are several options that will cost less than $300 and by careful shopping, you could be bit under $250.   (Both of my systems listed below are under the $300 price...  I seem to recall you need a Passmark rating of about 2000 per stream to transcode both 1080p audio and video using Plex.)

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Just swapped in that Intel PCI-E network card (after disabling Reaktek Ethernet in the BIOS).  1080p (and even 4K) video now streaming smooth!

 

Thanks so much, Frank!!!!  I'm unbelievably impressed that you were able to troubleshoot this, given how obscure the issue was.

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LimeTech and I were involved off-and-on for over a month working on this issue back in the Spring of 2015.  It is a real issue but (apparently) it has affected only a very few people and most of them have fixed by going to the Intel Network Card.  Although some of them may have upgrade to new MB and CPU with more horsepower and the problem disappears when the system can deliver the required number of CPU cycles to fully service the RealTek driver and all of the subsystems in the current unRAID operating environment. 

 

So it is not that I am so smart, I just happen to be the person who first identified it as an issue and was involved in the attempt to resolve it.  It would have been ideal if it could have been addressed without requiring a hardware update but that was the only truly viable solution.

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