add boot delay

If I shutdown my OMV (latest build for the Rock64, 4.1.8- Arrakis) the two USB data disks connected to the computer do not mount upon startup. I have to manually unplug the disks and plug them back in while checking the "disks" section of the OMV interface until they spin up and are mounted. Can I add a boot delay, or root delay, to give them more time to mount, and if so where do I add this? I'm able to ssh from another machine into the Rock64 running OMV, so I assume could nano into some file and add the delay, if that is the problem. I hope the question and problem I am having is clear.

I am open to any other solution that will fix the problem. I only know enough to get myself in trouble so please be clear with any instructions.

Thank you!

this problem seems to be solved. there were many people that gave suggestions but the most awesome user tkaiser checked in on IRC and it turns out maybe, sorta, could be, who knows was the problem. I did recently upgrade and apt-clean the OS. I can't explain it. It didn't work for several weeks and now it works. I don't care to be a negative nancy and everything else with my installation has been superb.

I'm seriously such a nubbins but thanks to everyone on IRC and I encourage anyone having a problem joining.