I recently decided to replace the SD card in my Raspberry Pi and reinstall the system. Without any special backups in place, I turned to rsync to duplicate /var/lib/docker with all my containers, including Nextcloud.
Step #1: I mounted an external hard drive to /mnt/temp.
Step #2: I used rsync to copy the data to /mnt/tmp. See the difference?
Step #3: I reformatted the SD card.
Step #4: I realized my mistake.
Moral: no one is immune to their own stupidity 😂
This. I made a similarly boneheaded mistake a few months back and lost a fair amount of stuff. Thankfully 95+% of it was ancient program files and such that gave me a good excuse to go through and make some much needed cleanup actually happen for once.