If you there's no SLAs to engineer for, just set the target at zero, and drive your cost to zero as well. So you have to design for _some_ defined value of reliability.
Backblaze's famous reports put HD failure rate is ~1.39%, so for the 11 9s you get as a guarantee from S3. Assuming nothing else fails, you'd need at least 6 independent copies to get that, plus all the effort to engineer recovery, and constant upkeep.
Suddenly, S3, even when considering bandwidth costs, seems like a steal.
Backblaze's famous reports put HD failure rate is ~1.39%, so for the 11 9s you get as a guarantee from S3. Assuming nothing else fails, you'd need at least 6 independent copies to get that, plus all the effort to engineer recovery, and constant upkeep.
Suddenly, S3, even when considering bandwidth costs, seems like a steal.