Problems with Roon Core on Synology DS218+ / High CPU Usage

I regularly encounter serious performance issues (Music stops and Roon Core cannot be found anymore) which can last for days and need some help!

My setup:

Roon Core on Synology DS218+ with 10GB Ram and 2 x 6TB HDD (abt 2TB used on HDD incl 1.3TB music)

  • Roon Library on 250 GB SDD attached to Synology via USB 3.0
  • Synology 218+ is connected to my Fritzbox via Ethernet
  • Most of the time I hear music via my Linn Majik DSM streamer which is also connected to the Fritzbox via Ethernet
  • Music Library (about 1.35 TB, abt 85.000 songs, with about 40 pct in lossless ALAC file format, most of them 16/44, some with higher resolution but max 24/96
  • Roon Software on all my devices is the lated built 416 published a couple of days ago, but the problems are still there

So hardware and software is or should be in full compliance with recommendation and my network configuration should also not cause any problems as we are streaming HD videos via Netflix, Apple TV and Amazon without any issues.

Whenever I do encounter the probems the CPU usage of the Synology DS 218+ is extremely high, i.e between 90 and 99 pct and I can see that this is only due to Roon Server using tremendeous amount of CPU power and not to any other programm running on the Synology.

When Roon is working properly the CPU usage of the Synology goes down to 5-15 pct.

Quite often the problems occur after I have added new music files to the library, so the high CPU usage could be due rescanning of the music library.

On the other side Roon was running properly for a couple of hours today and is now not working anymore although I have not added any files to my library.

Would be very happy to learn the reason for my problems.



Unfortunately, the Celeron processor in that NAS is insufficient for Roon, see

The following in the second link is especially relevant to the problem you are having:

CPU cache is also really important to an app like Roon. Some CPU series (Celeron, Atom) are severely cache constrained.


many thanks for your quick reply.

Ofcourse I am fully aware that the DS218+ CPU is by no means a Formula 1 racer.

However it is also not simply “insufficient for Roon”:

At this very moment Roon is running very smoothly with a CPU usage of 12 pct only (Roon Server using 1.2 pct only!) and I have sometimes used Roon for many hours / days without dropouts. It’s also not a question of HiRes files as the dropouts are not limited to HiRes files.

Obviously the DS 218+ is absolutely “sufficient” for playing, but sometimes the Roon Server is - for whatever reason - temporarily completely using the CPU resources.

I guess that this is somehow linked to “library organisation” in the backround and I wonder if I can improve the performance by making some changes to the present settings.


Database is likely to hit the processor cache hard, which would explain what you are observing. While Roon’s processor recommendations may seem pessimistic, they are likely chosen to avoid the kind of worst-case behavior you are experiencing.

You could try to temporarily disable the analyzing process in the Roon settings and check if it makes any difference.
Odds are the cpu might be the cause, but i have also seen behaviours like this triggered by something else (even on an i7 cpu).


as stated before I am well aware of the shortcomings of the DS218+'s Celeron processor and please be rest assured that I have read the Roonlabs recommendations before buying the DS218+.

If the DS218+ would simply not work I would immediately change to a Rock/Mock/Nucleus etc i7 solution, BUT Rooncore on the DS218+ is working excellent for weeks before - often after addition of new music to my library - having problems apparently caused by Roon Server’s high 218+ CPU utilisation.


Dear Christopher,

many thanks for your recommendation to disable the analyzing process in Roon settings (would have been my next step in any case, but happy to get this hint form on of the top experts as well :grinning: ).

P.S.: Also many thanks for your excellent work on implementing Rooncore on NAS :pray::pray::pray:

A brief update:

It looks as if I have solved the problem with the performance breakdowns :grinning:

  1. I have cleaned up my library (Settings–>Library–>Library Maintenance–>Clean Up Library

I had a significant number of deleted tracks and files not associated (anymore) with a storage location. This was probably due to about 30.000 songs I have re-ripped in the last year from cds into lossless format (previously many years ago ripped in mp3 or aac file format:face_with_raised_eyebrow: ) and other maintenance work on my music library.

  1. Backround Audio Analysis Speed (Settings–>LIbrary–>Backround Audio Analysis Speed) set to OFF (Previously Throttled)

  2. On-Demand Audio Analysis Speed (Settings–>Library–>On-Demand Audio Analysis) set to Throttled (unchanged form previous setting)

The performance is now really acceptable for me: After adding a couple of new songs and making changes (proper artist spelling etc) to about 250 songs, the CPU usage went up to 90+ pct for a couple of minutes while Roon was re-indexing the library but then went down to <10pct.

Roon is now working without any issues for about 5 hours, so problem appears to be solved and might have been due to the “uncleaned” library.



I am once again facing the same performance issues as described in my initial post of April 29th.

This only happens after I have added new files to my music library but it might take a couple of days before I Roon is working properly again.

To stop adding files to my library is no option :wink: so I think there is no other way than to take the core away from the underpowered Synology DS 218+

I am thinking of buying a NUC and install Rock, alternatively the Roon Core will move back to my iMac.



I do not believe this is a hardware issue with your Synology. I believe there is a defect in the Roon software that shows itself frequently when the core is on Synology (though I’ve seen it on other HW as well). You may take a look at some of my other posts on this issue. I have a top-of-the-line Synology with power to spare, and I have many similar symptoms.

Hi John,

many thanks for your hint.

Could really be a software issue: I am no computer scientist at all but cannot imagine that scanning a couple of new songs can be so demanding that the Synology CPU usage goes to 100 pct for a couple of days…

I have moved the core back to my Imac (late 2017 modell with I5 CPU, so definitely no high end model) and left the music files only on the Synology.
Roon is working smoothly now. Only disadvantage: The Imac has to run if I want to listen to music via Roon.


Jens, you would really enjoy a ROCK if your budget allows.


this - NUC with Rock - is exactly what I will eventually use as a Core.

Just not sure
a) if I should go for a fanless solution
b) which NUC (i3, i5 or i7)


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I have similar problems (sustained CPU load surge after a few hours of use) running Roon core on my MacBook Pro (2.7GHz i5, 8Gb RAM, SSD). The MBP overheats when that happens. Only solution I’ve found is to quit Roon and restart when it happens, then Roon runs fine for a few hours until it all happens again. After I posted a support request, other Mac users said they’re having that problem too.

A very late reply to this thread but just another $0.02 to contrib. I, too, ran into a similar issue (which popped up with extremely long delays in moving around the GUI) early during a trial when I migrated 40k+ tracks to a new Synology DS218+ running Roon with DB on a USB SSD. I traced it back to background analyzing as well and ultimately just decided to let it do its thing until it was done, and I actually jacked up the priority to 1 Core in order to get it done more quickly. I posted in this forum a few days ago if you’d like more info.

But by accident I observed an interesting fix: the slowness was happening while background analyzing all 40k+ files. About half way through I had to shutdown the NAS to move some cabling, and when I brought it back up Roon was showing that it was now only background analyzing about 20k files, and since then it’s been completely normal wrt speed. So either the reboot alone fixed something that was stuck, or there’s some issue in the software with managing a large queue/buffer of tracks to background analyze, as it appears that cutting the queue in half (assuming that happened because on reboot it only queued up tracks that had yet to be analyzed) helped other parts of the software which interact with remote clients.

Just one data point, but the above thread was helpful in my debugging so I thought I would share back.

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