Library Scan Prevents User Streaming

When the library is scanning no users are able to start a stream (local or remote). This issue is compounded by the fact that the library update appears to have slowed down significantly. It takes about 1 to20 seconds on each movie when the normal time is usually around 1 second. This results is the server becoming unresponsive to end users. The server now also cans all my music. This also freezes the server.

**As I sit here right now, I am unable to start a stream. If I kill the library refresh it works fine. **

Mac Mini (late 2012) i7
Mac OS X 10.11.3
Plex Server 0.9.16.0.1754
Attaching Plex Media Scanner.log
Attaching Plex Media Server.log

I will send other logs upon request.

Thanks for the help, Been a LONG time plex user.

In your individual library folders go to Edit Library --> Advanced and is the “Enable Video Preview Thumbnails” checked? (it IS checked by default). If it IS checked, this may be the cause of your long update per movie time as it creates hundreds or thousands of thumbnails. Over time and as you add more media you may notice your drive space on the drive you run your server is near full and this will further reduce your speed and may also be why your server cannot stream and update at the same time. Try unchecking that box in all your libraries and then updating your library, then optimize your database, clean the bundles and empty the trash and see if that helps your issue. The thumbnails can take up tens or even hundreds of GB over time as you add more and more media.

Update:
The problem is likely on my side. I noticed that my Synology, where the movies are stored, was filling up quickly. It turns out Cloud Station, with its versioning “feature” filled up 5TB worth of space in short order. Not only did that put pressure on the disk space available it also must have done a ton of writes to fill up all that space which may have interfered with the library scan.

I removed cloudstation and freed up 5TB of space.
I restarted the Mac Mini Server
I restarted the Plex Server
I just did a scan and all seems to be working again.

Bizarre. Hope it lasts.