Slow library scans on Synology DS923+

[Zeryther]

Hello,

I have been using Jellyfin for almost a year now and recently migrated my cloud-hosted instance to a new Synology DS923+ on my local network. So far, everything has been working well, except for one problem: Library scans are painfully slow, taking multiple hours to complete.

There seem to have been some folks on Reddit etc. who had the same issue over 2 years ago, but I still couldn't really find a solution or even understand what causes the problem. While the library scan is going on, CPU usage is pretty low but the Web UI becomes almost unusable as requests take forever to complete or never complete at all.

My library has just over 100 movies and some TV shows and anime and is just 4.7 TB big, which shouldn't be that big of a deal. In the cloud library scans were very fast, so I'm hoping someone else here who uses a Synology for their media server knows the issue?

I disabled real-time monitoring yesterday which pretty much gets rid of the issue, at the cost of Jellyfin not indexing new media files. This is a problem when I have currently airing shows with weekly releases, forcing me to complete the library scan first before being able to watch it.

Edit: The Jellyfin instance is hosted through a Docker container on the Synology.


I would appreciate any help with this. Thank you!

[Venson]

Hey @Zeryther

Do you use any plugins like Jellyscrub, Introskip or OpenSubtitles?
Those can extend the scan time significantly

[Zeryther]

Hello @Venson

Out of all of these, I only use the OpenSubtitles plugin. Just tried disabling it, but the scans are still very slow.

I previously also tried to spin up a fresh Docker container with Jellyfin and out-of-the-box I'm experiencing the same slow library scans.

[antpic1]

Did you ever find a solution to this? I have a very similar set up with the same issue. Even if I only add one new movie/tv show it takes 12+ hours to scan everything. No extra plugins either...

[TheDreadPirate]

The root cause isn't logged in jellyfin so it's hard to say what the problem is. IMO, this is probably something you should ask in a Synology forum or sub-reddit since you will have a much larger user base of people with Synology NAS's who know their way around it.

[zoOe]

Same issues here, scanning movie library with 65tb took about 20 hours, scanning series (60tb) is now running since 42 hours. Initial scan with Plex was 4 hours per library. There are several issues posted on github and elsewhere, but without a solution. I already disabled every not needed stuff like chapter extraction or similar before i added paths to the libraries, also not using image grabber/extraction. This is a real bummer as Jellyfin is totally unusable when a scan is running. I fear to update metadata regulary if thats a default behaviour.

[TheDreadPirate]

How many plugins do you have running?

[zoOe]

Standard ones + Merge Plugin.

I am scanning a cloud service, documentation says that currently image extraction cannot be disabled (even unticked) and that can cause performance issues. Seems like that. Just gave Emby a try and all is running flawlessly.

https://jellyfin.org/docs/general/admini...rage#cloud

Seems known since Jan 2020 according to Github so i dont think this will be fixed in a short time.

[skribe]

Standard ones + Merge Plugin.

I am scanning a cloud service, documentation says that currently image extraction cannot be disabled (even unticked) and that can cause performance issues. Seems like that. Just gave Emby a try and all is running flawlessly.

https://jellyfin.org/docs/general/admini...rage#cloud

Seems known since Jan 2020 according to Github so i dont think this will be fixed in a short time.

I use Jellyfin with cloud storage myself without issue, so I don't suspect that's actually the root cause here. You're welcome to share logs and we can see if there is any information there. It doesn't even really sound like you're experiencing the same issue as the OP in this thread.