Backup Methods
As far as I can tell, there are two main paradigms of local backups. You either make an archive, and keep continuous archives, or you make plain copies of the files, but then as backups build you use links to point to the unchanged files from the last backup. Since I'm backing up a lot of family photos, I chose to use copies and links through rsnapshot, as that feels like it will use less space in the end.
Setting up rsnapshot
After installing it through my package manager, it was relatively simple to setup. The default location for the config file is at /etc/rsnapshot.conf, and for my use case most of the defaults were fine. The only thing I had to change was to set snapshot_root to a folder called backups on my smaller hard drive, set the retain values to keep 6 daily backups, 7 weekly backups, and 4 monthly backups, and finally point the backup values to the folders I wanted to backup, being /home and /mnt/black
Automating rsnapshot
To make this backup routines actually run on a regular schedule, I added them to the cron tab using sudo crontab -e. The specific rules I entered were:
# Run daily backups at 00:05 daily
5 0 * * * /usr/bin/rsnapshot daily
# Run weekly backups at 01:05 on Sundays
5 1 * * SUN /usr/bin/rsnapshot weekly
# Run monthly backups at 02:05 on the 1st
5 2 1 * * /usr/bin/rsnapshot monthly
Notice that I scheduled each job to run at a different hour, to give each one plenty of time to not run into another one.
Restoring a backup from rsnapshot
Finally, in the case that something goes wrong, we use rsync to restore backups made by rsnapshot, since that is what it's using in the background. The specific example I tested was having a folder at /mnt/black/dummy backed up to /mnt/Vault/backups/daily.0/dummy/mnt/black/dummy, which I restored using the command:
sudo rsync -av --numeric-ids --delete /mnt/Vault/backups/daily.0/dummy/mnt/black/dummy /mnt/black