Using PLEX on EX4100 has high CPU usage and poor streaming performance

Help please!

I’m having problems with streaming movies using PLEX running on an EX4100.
The CPU utilisation is very high and the movie keeps stopping (almost as if it is buffering). Memory and bandwidth usage are low however. Also, there is plenty of room on the array. Pretty sure I’m running latest firmware as well.

Any ideas anyone?


Hello matthewfenn,

I would suggest you to run diagnostic test on the device to isolate the issue.

Refer the link mentioned below for more information.

Hi Matthew,
I have the same issues, it seems this model isn’t powerful enough to stream using the plex app on the NAS. My workaround is to use a pc as a proxy and the EX4100 only for storage… PR4100 is the way to go if you stay with the WD products…

@Neo33, thanks for the advice - though I can tell from the performance monitor that it was the CPU that was getting hammered, not the disks - and when I ran the performance tests, as expected, they showed everything was fine.

@cemarsh , I’d also done some more searching and testing myself… What I discovered was this.

I’m pretty much exclusively playing back the video via a 4K AppleTV. When I used MakeMKV to rip an 1080p HD DVD, it created a file that was roughly 5-6Gb in size, depending on the movie. If it was an old 720p SD DVD, then the file would be roughly 2Gb. Both of these files would have trouble when being streamed from the Plex server on the EX4100 to the Apple TV. On the other hand, if I ripped a Blu Ray, it would create a file around 16Gb but this file would have no problem streaming onto the Apple TV…

My theory is that the Apple TV is demanding 4K content, and therefore the Plex Server would attempt to send that. For the Blu Ray, the file is already in the right resolution, so it just reads the file and streams it. For the lower resolution files, it has to upscale them before streaming…

Now if only I can get the Apple TV to do the upscaling instead of the EX4100, then I think I’d be OK.

As a work-around, what I’ve been doing is using Movavi (a paid for product) to convert the .mkv files into .mp4 files instead - effectively converting them into files that are “4K Apple TV ready”. These then stream just fine.

The downside is that if I wanted to stream a film to a different device, that wasn’t 4K, I would probably run into the same processing problem as it needed to downscale… not actually tested that though yet!

Of course, watching an old 720p DVD on a 55 inch 4K telly (or even an 8 foot wide projector screen) really shows up the low resolution and tells me I never want to purchase anything but a blu ray again! Preferably a 4K one! Now if only iTunes would only sell everything in 4K! (And yes, I know that re-releasing a film as 4K is only possible if it was filmed with real film that can be rescanned at 4K resolution or if it was originally filmed in 4K digital format. :frowning: Just wishful thinking! )

I would concur with all of your tests, using the EX4100 was a simplification of my network. I have a HTPC (i7/16Gb ram) as well as 24 core server. My desire was to just have a much simpler solution dedicated to streaming media content to multiple devices. I use Plex and Playon. My plan is to upgrade to PR4100 or build my own…
I believe ultimately you will come to a similar conclusion. It should be much easier and it is…

good luck…

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