Wednesday, June 27, 2012

Cloud vs. Local Storage Costs

In earlier posts I pointed out that for long-term use "affordable cloud storage" wasn't, because compared to local storage:
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.
The graph that the model generates shows that cloud storage is competitive with local storage only if (a) its costs are dropping at least at the same rate as local storage, and (b) both costs are dropping at rates above 30%/yr. Neither is currently the case. If we use the historical 3%/yr at which S3's prices have dropped, and the current disk industry projection of 20%/yr, then the endowment needed for cloud storage is 5 times greater than that needed for local storage.

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.

Monday, June 4, 2012

Storage Technology Update

Last month marked the 60th anniversary of plastic digital magnetic tape storage.
The IBM 726 digital tape drive was introduced in 1952 to provide larger amounts of digital storage for ... IBM’s 701 computer.
As Tom Coughlin points out:
The current generation, LTO 5, has 1.5 TB of native storage capacity.  According to Fujifilm and others in the industry, magnetic tape technology can eventually support storage capacities of several 10’s of TB in one cartridge.  Much of these increases in storage capacity will involve the introduction of technologies pioneered in the development of magnetic disk drives.
While disk drives are coming to the end of the current generation of technology, Perpendicular Magnetic Recording (PMR), tape is still using the previous generation (GMR). So tape technology is about 8 years behind disk, making this forecast is quite credible. And it is possible that by about 2020 the problems of Heat Assisted Magnetic Recording (HAMR) will have been sorted out so that the transition to it will be less traumatic than it is being for the disk industry.

Below the fold I look at disk.