Absolutely right, assuming the data you keep on S3 is mission critical (for me it's mostly just archival stuff, logs and such, that we never touch but have no p

Absolutely right, assuming the data you keep on S3 is mission critical (for me it's mostly just archival stuff, logs and such, that we never touch but have no particular reason to delete since S3 is so cheap, so we don't worry about backups). But even if your data does matter, spending $1000 to back it up separately is not a no-brainer, depending what your data is actually worth to your business and how likely you think it is that S3 will lose it. Assuming your data is worth a million dollars, then spending $1000 to back it up implies that you think there's at least a 1 in 1000 chance that S3 will lose it all. I don't know what probability I'd assign to "S3 loses all my data", but I do know that the particular data I store there is not valuable enough to make it worth backing up elsewhere. If my data actually mattered, I'd work out the math and consider alternatives. I will say this, as a word of warning - I would never use Amazon's durability claims ("Amazon S3 is designed to provide 99.999999999% durability of objects over a given year") when doing such a risk vs. cost assessment, because the real risk is not that the expected failure modes will "get you", but that something totally unknown and unpredictable will happen, i.e. someone at Amazon totally fucks up a staging push and sends it live to production instead, and the replication system goes nuts and starts corrupting everyone's data irretrievably before anyone realizes what's going on, or something like that. SLAs and durability claims don't account for stuff like that, but it's still a risk. Of course, there's also the "cover my ass" and "I'm not paying for this anyways" factors to consider - if you would likely lose your job if the data in question was lost, and your personal finances are not affected one bit by the company spending an extra $1k/$10k/$100k on backups, then even if math tells you it's a waste for the company, you might as well do it, because as long as it's not too much of a pain to set up it will help protect you. The calculus always changes when it's other people's money you're playing with...