Backups are done from my main PC (and possibly other places) to /var/nas/backup. Periodically, this is copied to an offsite backup drive, which is mounted:

sudo mount /dev/sdd1 /mnt/offsitebackup

There is also archive content at /var/archive, which is sole copies of things that are only nice-to-have. They aren't backup up to offsite because it is not vital that these be retained.

Then we rsync like this, available as rsyncToOffsiteMedia in /home/dwheele on Joshua (it won't run from /var/nas because execute is not included in /etc/fstab):

#!/bin/bash
rsync -a /var/nas/backup/ /mnt/offsitebackup/backup

Note the source directory has a trailing slash. This means to copy the contents of this directory, and to not create a backup directory inside of the source directory.

To disconnect:

sudo umount /dev/sdd1

Then the offsite drive can be moved off site.

[3/20/2021]