Right now I’m creating a nightly restic snapshot of my server on borgbase and on some spare drives, and keeping the snapshots forever. There’s a ton of daily churn in my data though, between databases and logs and other files that don’t constitute ‘real data’ but might be needed to restore the app.
I guess OPs question is more about what makes you comfortable.
Is your drive only big enough for 2 backups or is it big enough for hundreds? If it was half that size would you still be happy with the number of backups? A quarter of the size?
Kinda depends on what it’s for. My server? IDK, 2 days. Maybe have a dedicated weekly/monthly backup left behind. PC? Honestly just the latest is fine.
But it’s a 10tb drive, so I’ve got months of backups even if they’re running continuously. It’s less a how comfortable I am and more a how much can I afford. (a lot more before the shortage)
I also explicitly purge stuff that’s constantly changing like logs. I don’t care for logs in my backups. Only on the live machine.
I have about 750GB of irreplaceable files on my server so I want a really solid history. A couple of days backup is no where near enough to give me peace of mind 😅
3 2 1 offsite backups typically happen a lot less often than local copies or local backups.
I also don’t really consider any machines data to be irreplaceable. If I lose my phone I want the latest backup. But taxes or photos I care for? Those are an entirely different backup, and those aren’t incremental. They’re just what they are.
I have Nextcloud on my server which stores all those documents and photos etc. I have nightly offsite backup as well as backing up to a local borg repo on a separate drive.
But as it’s that important to me, I also do a once-yearly backup of non-encrypted files to M-Disc, with two copies, one stored at my mother’s house. This way if my house burns down and I’m inside it, my family can still get (most of) the precious memories without needing to know how to access a borg repo and without having to know how to download from Backblaze object storage.
I’m just a little bit paranoid about losing things after that one time I dragged from a USB stick to my computer and when it was done moving the files they were all corrupt, and didn’t exist on the USB stick anymore either. Thanks Windows, a whole holiday of photos gone.