Im runing OMV2 (didnt upgrade since installe because back then there was a bug that broake the system while having automated updates on)
Thats my System.
As you could see, IO-Wait is the main CPU usage.
The System is a HP Pro Liant Micro Gen 8 Server.
I do not use the onboard soft raid controler for the data drives. Only the OMV OS runs of a single 2,5 disc thats conected with the on board SATA (raid) controler.
For the data drives: I use a HP P420 hardware raid controler powering 2pc 10TB drives and 2 1TB SSDs as cache and 1GB RAM.
Ive upgradedt the Stock HP Micro Server with the biggest CPU and 16GB RAM.
What caused the load you saw in the pictuer was 3 different SMB coppy jobs only reading form the OMV server.
so I did run IOTOP and found that jbd2/sdb1-/8 is causing the load.
also while VMs are online, VirtaulBox (also the clients are "sleeping") causes a very hi IO Wait
And also I see a flush-8:16:
and, I was not able to catch it, but while all virtualbox clients where off, I had jbd2/sdb1-8 causing a load of 99,9% in line 1 and smb 99,9% in line 2
for just 4 SMB files transfers read only from OMV
This is what TOP gives me.