Restic doesn't write your files 1:1 to B2, but instead chunks their content into files according to a configurable pack size (16MiB by default). If you have a very large amount of data, you could look into increasing the pack size, although that comes with its own risks (see the docs above).

Does it have to be B2? If you want free egress and cheap storage, you may also consider Hetzner's storage boxes.

I use B2 for my restic Backup. Currently i have about 100GB stored there and it says i have about 100,000 files stored.

With the adjusted calculation of the blog you posted for 10TB of 50KB files, adjusted to the mean file size of my restic repository 10 TB of 1MB files:

Transaction fees: 10,000,000 / 10,000 x $0.004 = $4

My Laptop has a mean file size of about 16 MB per file on the local restic repository.

EDIT: Forgot a resume, i do not think you need to worry about it too much. But maybe verify the amount and type of data you want to backup and use calculators to calculate the real cost, also you can always test it by creating a test dataset and then do a backup and recovery scenario and then use this to derive an estimate.

Question: What does BackBlaze B2 give you that BackBlaze's personal account doesn't?

I’ve always wondered, doesn’t Backblaze cut exfiltration costs to zero if you proxy it through cloudflare? Why isn’t that an option so you’re only paying for storage costs and not bandwidth?

Backup as a zip? Small files warped up in one big file. Only backup what you can't restore from somewhere else. I think B2 can ship you a HDD to restore from if I remember correctly.