Hi all. My cache drive filled up today, and I had been kicking the can down the road on upgrading it and my video card, and adding another HDD to the array, so tonight I decided to stupidly tackle all three. I stopped the docker, stopped the VM, ran the mover, turn the server off, installed everything, removed old SSD and video card, and booted back up. I could not slot in the cached drive, it would say "cache - too many missing/wrong devices", but if I slot in the new HDD, the array would come up. it would not let me do anything without adding the new HDD to the array. now I am stuck waiting for diskclear to complete over the next 20 hours, but I can't bring any of my dockers or VMs online, and I still will need to get the cache drive slotted in after. I am guessing there's not an easy way to bring my dockers online while this runs? Anything I should know for when this operation completes? I am hoping I can just take the array back offline and slot in the cache drive once this completes.

If the docker containers are using /mnt/user you can use the in the array for now.

Yeah, they use /mnt/cache

You could change them, but probably best to just wait.

Ok problem, I ran the mover, but didn't verify what was on my array, it doesn't look like it worked because I don't see that data on my array. So I still have my old cache drive, should I plug it back in and copy it over? Or should I plug it into another machine and copy it over? 

You can do whatever is easier.

Plugging into the sever seems like the fastest route to copy 2 TB of data over, but once I plug it in, what should I do to make sure I don't accidentally preclear my cache drive but still make it available to copy files off of?

Just don't click preclear, it won't start on its own.