Quote from: Forsyth Jones on Today at 07:49:49 PM

copy the entire current blockchain to an external HD or SSD (whichever I have available), but first I delete the outdated backup

This is how you lose your data! Imagine this: you delete your backup, and right after that your main drive fails. Data gone.

Quote

So there's nothing I can do to optimize how backups are handled, right? I've already considered that possibility.

If you want to update for instance an offline version of Bitcoin Core, rsync would work. The first time, copy everything, and after that, only update the data.

For regular backups, play around with rsync --link-dest= a bit. Something like:

Code:

mkdir /path/backup/todaysdate
rsync -avh --link-dest=/path/backup/yourlastbackupdate /home/user/.bitcoin /path/backup/currentdate

This makes your backup grow maybe 6-8 GB per week, plus 12 GB for chainstate. The latter will still consume a lot of disk space if you do frequent backups, your blocks directory will grow only for the new data. And you'll leave your previous backups unchanged.