I recently used my prototype economic model of storage to make a more detailed comparison. As usual, the necessary caveat is that this is an unvalidated, prototype model. The actual numbers should be treated with caution but the general picture it provides is plausible.
The model computes the endowment needed to store 135TB of data for 100 years with a 98% chance of not running out of money at various Kryder's Law rates for two cases:
- Amazon's S3, starting with their current prices, and assuming no other costs of any kind.
- Maintaining three copies in RAID-6 local storage, starting with BackBlaze's hardware costs adjusted for the 60% increase in disk costs caused by the Thai floods since they were published, and following our normal assumption (based on work from the San Diego Supercomputer Center) that media costs are 1/3 of the total cost of ownership.
UPDATE 3 Sep 12: As I was working to apply our prototype model to Amazon's recently announced Glacier archival storage service, I found two bugs in the simulation that produced the graph above. Fortunately, they don't affect the point I was making, which is that S3 is too expensive for long-term storage, because both tended to under-estimate how expensive it was. Here is a corrected graph, which predicts that S3 would not be competitive with local storage at any Kryder rate.