>>10556
To make it simple, backup the
contents of one encrypted container to another. Do not backup encrypted images, as you'll be doing 500GB every time. Instead just mount the two images and backup their internal folder structures as normal, as if you were backing up an unencrypted location.
Afaik, there's no super easy way to do a minimal backup where you only update the sectors of the image/files that have changed, although there is probably some specialised software out there that does that by tracking sector hashes or something (although this would presumably have to rescan the whole contents of the source anyway to spot differences, or be part of the fundamental file system like
>>10564 suggests).
It is simpler just to use FreeFileSync and copy-overwrite the files with newer modification timestamps to the backup. db files can be pretty big–maybe on the order of 10GB for hydrus, but 10GB is ultimately not a big deal for local backups once a day/week/month. The media files are just jpgs and whatever and copy in reasonable time as they would in any other situation. I do a weekly backup of a 1 million file hydrus db to a usb drive, and it takes about five minutes to scan and five minutes to action. Easy peasy.
I don't know enough about veracrypt to comment cleverly about it. If you are putting files in an encrypted container, it is easy, but if it does some mickey-mouse on-the-fly per-file encryption, then your situation may be different.