The math doesn't come close to replacing tape - basically once you go north of 100 terabytes (just two containers - at my prior company we had 140 containers in rotation with iron mountain) Glacier doesn't make financial or logistical sense. Far cheaper and faster to send your LTO-5 drives via driver.
It may not make sense today. Amazon is notorious for betting on the far future. They're also raising the bar on what archival data storage services could offer. When you ship your bits to Amazon, they're in 3+ DCs, and available programmatically.
Separate from the play for replacing tape, there's also the ecosystem strategy. When you run large portions of your business using Amazon's services, you tend to generate a lot of data that ends up needing to be purged, else your storage bill goes through the roof. S3's Lifecycle Policy feature is a hint at the direction they want you to go - keep your data, just put it somewhere cheaper.
This could also be the case where they think they're going after tape, but end up filling some other, unforeseen need. S3 itself was originally designed as an internal service for saving and retrieving software configuration files. They thought it would be a wonder if they managed to store more than a few GB of data. Now look at it. They're handling 500k+ requests per second, and you can, at your leisure, upload a 5 TB object, no prob.
But maybe you're right. The thing could fail. Too expensive. After all, 512k ought to be enough for anybody.
Thanks very much for the insight - what you are saying actually makes a lot of sense in the context of systems inside the AWS ecosystem. After all, they need to archive data as well. Also - my 140 container example w/Iron Mountain was Pre-versioning and always-online differential backups. We basically had a complex tower-of-hanoi that let us recover data from a week, a month, six months, and then every year (going back seven years) from all of our servers. (And, by Year seven, when we started rotating some of the old tapes back in - they were a generation older than any of our existing tape drives. :-)
Clearly, with on-line differential backups - you might be able to do things more intelligently.
I'm already looking forward to using Glacier, but, for the forseeable future, it looks like the "High End" archiving will be owned by Tape. And, just as Glacier will (eventually) make sense for >100 Terabyte Archives, I suspect Tape Density will increase, and then "High End" archiving will be measured in Petabytes.
Have you considered the cost of the tape loaders? Our loaders cost significantly more over their lifetime than the storage costs of the tapes themselves.
The tradeoffs will be different depending on how many tapes you write and how often you reuse them.
Until I took over backups, and instituted a rotation methodology, the guy prior to me just bought another 60 AIT-3 tapes every month and shipped them off site to Iron Mountain.
Agreed - how-often you re-use tapes (and whether you do) - has a dramatic effect on "system cost" of your backup system.
