I noticed this in dmesg after inserting a hard drive into my backup dock:

The raid array works fine, nothing went down all VMs running, if I had not seen that I'd never know. Should I be worried? What would cause this? I do have two drives that are failing, but it should not be crashing the raid software. They are still seen as ok, but there are lot of smart errors.

Also, not sure if it's related, but when I go to mount a drive (non raid) I have to turn it off/on several times before the mount actually works. Otherwise it says it's busy and already mounted.

If you've got sefgfault & 2 drives known to be failing, I'd backup everything, then run fsck on it.
I'd also start thinking about possibly needing some new disks....

Yeah I always have backups. The replacement drives are on their way. They just hit toronto last night, hopefully be here by tomorrow.

But should I worry about segfaults? What could cause that or should that clear up once I replace the drives?

The two drives that are failing are actually brand new, so that kinda sucks.