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 😂
Everyone else is gonna be like “if you don’t have at least 3 backups of something blahblah” but you know, not everyone has the finances for that, so advice from a cheapskate computer nerd: when going through critical transfers/reformats/deletions like you were doing, ALWAYS try actually recovering stuff from the backup before you cross the point of no return. E.g. if the backup is a .zip, extract a few individual files from it and open them in their respective programs.