Relevant stuff is either on Github or Codeberg for dev stuff and on a openCloud Instance for other files. openCloud gets backuped daily. If I ever need to reinstall my computer(s), I need to reinstall tools mostly and sync everything again. Oh and as I just read it in the comments: I also have a parachute backup for images, iCloud stuff etc.

For personal files/media, I heard about the 3-2-1 method: 3 copies, 2 formats, 1 offsite. I'd likely want to add a complete self-contained toolchain to convert format with that offsite copy.

I'm not nearly as particular with my OS backups as I used to be. For instance Desktop personalization is minimal. I've used too many computers over the years to maintain much configuration beyond a small number of dot-files. Hobby code goes in Github/codeberg.org and some kind of cloud sync for my daily driver.

Another thing that ended up happening naturally is that I keep hard drives of old computers when I upgrade. They serve as point-in-time snapshots. I haven't made it a point to be able to necessarily read all of them but it doesn't take much like having a number of USB-disk/media interface adapters around.

I don't have too much data but I use https://github.com/denzyldick/siegu

I just have a cron job running a simple bash script on all my machines (Linux, macOS) that compressess all my personal files (mainly configs and docs) on a daily basis. It then uploads it to a local NAS (just two USB sticks connected to a Raspberry Pi; might upgrade to a proper homelab at some stage). This is in turn backed up to Filen (Germany based). The backups include 30 daily backups + 12 monthly backups.

As for system-level backups, I just use btrfs automatic snapshots (via Snapper).

- Daily restic backup to an internal SSD of my desktop,

- Daily snapraid backup of my NAS

- Once a month I save my desktop to another offline SSD

- Once a month I save important NAS files to an offline HDD

Weekly write of my files to an external HD. I swap the HDs monthly with off-site copies.

Mac: I use Parachute Backup to keep a local copy of my iCloud files and photos on an external drive. Backblaze backs the external drive and all local working files (roughly 16TB altogether) up for ~$100/year.