Hello everyone,

I'm running Unraid 6.12.15, and I'll attach my diagnostics below.

I'm noticing that my cache drive appears to stay active constantly, even when no VMs or containers are running. CPU usage remains around 7–8% at idle, which seems unusually high.

I wanted to troubleshoot this further using File Activity and Open Files, but unfortunately those plugins are not compatible with my current Unraid version, so I'm a bit stuck on how to identify what's causing the activity.

I'd really appreciate it if someone could take a look at the diagnostics and help me understand what might be happening.

Thank you!

tower-diagnostics-20260517-1158.zip

If you even have the Docker or VM services enabled under settings then they will keep files open on the 'system' share (which is on cache) so that probably explains what you are seeing.

That makes sense.Docker services are indeed enabled under Settings, so that probably explains why the cache drive never seems to go completely idle.

What I'm still trying to understand is whether this continuous SSD cache activity is considered normal behavior in Unraid, or if there’s something misconfigured on my system causing unnecessary activity.

If this isn’t normal, is there anything I can do to reduce or prevent the constant cache drive usage while the system is otherwise idle?

No. Running apps will always be doing stuff regardless of the OS, that's the whole point or you wouldn't be running them...

The RAM disk for Docker logs can reduce that a bit if it's just Docker-level logging but anything from the apps themselves will always cause usage.

Regarding CPU you can look at e.g. htop to find what apps use most of it, and choose not to use them if you think that's too much I guess...

Thanks guys.

@Kilrah So this continuous cache activity is probably normal, I am guessing, as long as even a single container is running.

But when I say “cache activity,” I don’t just mean that the cache drive stays active I’m also seeing constant writes to the SSD, sometimes up to around 600-800 KB/s even while the server is basically idle. Now why is that happening or Is that considered normal too?

That is completely normal in my experience. My server that runs just a handful of containers usually shows around that on my cache activity, and my server that runs over 80 containers shows well over that in nearly constant activity. If you are worried about drive health, at 500KB/s constant writing, it would take nearly 30 years to wear out the endurance on a 600TBW rated drive—this is obviously not counting any times of heavy write activity and only the background noise you are seeing. If you just want to identify what is causing it, I would just echo Kilrah's suggestion of htop, specifically the i/o tab.

Thanks everyone for the help and detailed explanations.

It looks like the continuous cache activity and low-level SSD writes I was seeing are normal behavior for an Unraid server with active Docker containers, and not an indication of any underlying issue.

@CandleSir's clarification regarding SSD endurance was especially reassuring, and I also appreciate the suggestions about using htop/i-o monitoring to further inspect activity if needed.

I’ll go ahead and mark this issue as solved, at a later time. Keeping it open for now, just in case.

Thanks again to everyone who took the time to help!