Glacier Deep Archive is the cheapest cloud backup option at $1USD/month/TB.

Google Cloud Store Archive Tier is a tiny bit more.

To quote the old mongodb video: If you don't care about restores, /dev/null is even cheaper, and its webscale.

Both would be pretty expensive to actually restore from, though, IIRC.

Quite expensive, but it should only ever be a last resort after your local backups have all failed in some way or another. For $1/mo/TB you purchase the opportunity to pay an exorbitant amount to recover from an otherwise catastrophic situation.

If you don't test your backups, they don't exist.

There is a free tier that accounts for testing, first 100GB of transfer out of AWS per month is free.

Yes, about $90USD per TB.

But I weigh that against data recovery from failed disks and the loss of the data I put in Glacier (family photos/etc). Then its dirt cheap.

Depends how big they are. My high value backups go into S3, R2, and a local x3 disk mirror[1].

My low value backups go into a cheap usb hdd from Best Buy.

1. https://github.com/nathants/mirror

Support for S3 means you can just have minio server somewhere acting as backup storage (and minio is pretty easy to replicate). I have local S3 on my NAS replicated to cheapo OVH serwer for backup