Earlier quoted context omitted.
I'd be willing to lose 100TB at once, assuming it wasn't every day. If there were a system where it lost even 20TB/day, I'd be interested, depending on what the tradeoffs were! I'd expect that to be pretty seriously cheap to offset it. That's why I'm asking what options people know about. If you know one that is randomly lossy but cheap, I'd be REALLY curious as to what their backend is!
I'd say most of the options people have proposed are in that range. Theres no backup, no simultaneous mirroring etc, which you are paying for with s3
Amazon S3 costs around $1/gb/year. Let's say it has 0% chance of data loss Suppose I can store something without any replication. Cost drops to $0.50/gb/year, 2% chance of losing all my data. If the value of my data is less than $25/gb, it makes financial sense to go for the unreliable option.
Much of my data is worth less than $25/gb. photos, video, old mail. Storing it on RAID is a waste of money.
besides, the chance of me deleting everything by human error is often much higher than the chance of hardware failure.
and some decent portion of those failures come with advance warning, so that you can save at least some of the data.