No actual data loss here, but the feeling of data loss.

After having my data scattered across several devices i decided to get a grip on it use a cloud. I'm too paranoid for a real cloud so i used a local nextcloud installation. That was done via docker and with a 2TB raid1-array.
I noticed that after restarting the server the cloud was somehow reset and pointed me to the setup-page, afterwards my files were already there. It did strike me as odd but i figured "maybe don't restart the server in the next time".
But i did restart it. And this time i had to setup the cloud again, but my files were gone. I got close to a heart attack, even though all those files weren't that valuable. I ripped one disk from the usb hub, connected it to my laptop and tried to mount it, but raid array. Instead i started photorec and recovered a bunch of files, even though their names were some random hex and i knew i'd spend my next weeks sorting my files. While photorec ran i inspected the docker container and saw that there were only 10GB of space available. After a while and one final df i found the culprit: the raid. For some reason the raid wasn't mounted at boot and docker created the volumes on the servers hard disk, same goes for the container data. After re-adding the disk to the hub i mounted the raid and inspected everything again. All my files were still there.

At no point did i lose my data, but the thought was shocking enough. It'd be best not to fiddle with this server in the next time.