Hi,
i just wanted to post this here, so that somebody else could find this as a hint.
I just migrated my UnRaid installation from a HP ProLiant Micro Server Gen 8 to a HP ProLiant ML10 Gen9 and after this migration i had a closer look at the CPU Usage and overall system performance (i was confused that everything went so well).
I saw CPU spikes every minute (or 45 seconds). In the first few days i thought this had to be a hardware error and i changed the Lan cable, Sata cables and so on. After this didn’t change anything i suspected a software issue in unraid, however nothing seems to change anything. Than i had a look at my docker containers and suspended all of them and started them one by one.
openHAB was triggering this CPU spikes with 25% IO wait every minute (on a Skylake Xeon E3-1225 v5).
Then i hunted for the thing or addon or rule that was causing this spikes. In the end it was the RRD4J Persistence Addon. I suspect that i just had too many items over a too long of a period of time for the database. So after disabling rrd4j, my io wait is down to 1-2%.
Hopefully this will help someone else. It took me over a week to troubleshoot this issue.
If this is in the wrong sub forum, feel free to move it.
[EDIT]
I don’t want to imply that the rrd4j binding is not performing or bad. This is surely an issue with my config of the rrd4j plugin. However i just wanted to make sure that if someone else got a similar issue that he or she could have a look at the persistence configuration.
[/EDIT]
Cheers
Andreas