True enough, but you do get a bit more than just storage from tarsnap. S3 provides storage and an API for uploading things to it, but you can’t just back up your files to S3. You have to figure out what files have changed, compress them, encrypt them, and index them so you can retrieve them again later, etc, etc. That’s a non–trivial amount of software to write. It’d be really great if someone had already done so… Oh look, someone did!
I could imagine purchasing that software for a one–time price, running it myself, and paying AWS for storage. But then I’d have to monitor it, troubleshoot outages, maintain things, etc, etc. Or I could pay someone else to do all of that. I’m not currently a customer, but I know which I prefer.
Several people have written that software. Duplicati, Borg, Arq for example.
> But then I’d have to monitor it, troubleshoot outages, maintain things, etc, etc.
None of these solutions free you from having to monitor your backups, including Tarsnap. Tarnsap requires setup on your server. You have to make sure it's running and backing up the correct files. And you really should verify you can restore a backup.
I'm really not sure what Tarsnap adds over these aside from saving you from having to sign up for B2 to S3 and punching in an API key.
Tarsnap preforms asymmetric encryption which lets you perform automated backups without needing to enter any passwords (or otherwise storing your encryption passwords in plain text).
Tarsnap does full deduplication across all backups for any given "machine", while still letting you independently remove any snapshots you like. i.e. no special "full snapshot" that must always be kept around, and no need for multiple full snapshots that have no deduplication between them.
I could imagine purchasing that software for a one–time price, running it myself, and paying AWS for storage. But then I’d have to monitor it, troubleshoot outages, maintain things, etc, etc. Or I could pay someone else to do all of that. I’m not currently a customer, but I know which I prefer.