Errors on devices that don't exist

I am getting Kernel errors every minute referring to 2 devices which don't exist:

Kernel: i/o error on dev dm-2

Kernel: i/o error on dev dm-3

When I check for the devices dm-2 and dm-3, they point to 2 encrypted devices which also don't exist (pls see below). I have dm-1, dm-2 and dm-4. But the drives fm2, and dm3 are not on my system.

Does anyone know how to find the source of that problem?

ls -l /dev/mapper
crw------- 1 root root 10, 236 Nov 29 11:48 control
lrwxrwxrwx 1 root root       7 Nov 29 12:02 sdb-crypt -> ../dm-1
lrwxrwxrwx 1 root root       7 Nov 29 11:48 sddrest-LV1 -> ../dm-0
lrwxrwxrwx 1 root root       7 Dec  2 13:43 sdg-crypt -> ../dm-2
lrwxrwxrwx 1 root root       7 Dec 23 14:22 sdh-crypt -> ../dm-3
lrwxrwxrwx 1 root root       7 Jan  7 12:43 sdi-crypt -> ../dm-4

Saw that but it wasn’t LV. In my case the problem were USB ports. I disconnected external USB devices and OMV or Debian wasn’t happy about it. Kept logging every 5 secs until I hard rebooted the server. Something is strange I guess. USB devices are designed to be hot unplugged so Debian or OMV should recognise this and not put the Kernel into such a logging frenzy.

One was a HD and one was a keyboard. It’s strange, omv should just stop mounting after say 10 tries, instead of flooding my log files every 2secs.