Adding cloud storage to the economic model

The next stage in building the economic model of long-term storage is to add the ability to model cloud storage, and to use it to investigate the circumstances under which it is cheaper than local storage. The obvious first step is to collect historical data on cloud storage, to compare how rapidly it is decreasing against the Kryder's Law decrease in disk cost. The somewhat surprising results from looking at Amazon S3's price history are below the fold. I'd be grateful if anyone could save me the trouble of getting equivalent price histories for other cloud storage providers.

CNI Talk on the Economic Model

I gave a talk at the Fall CNI meeting on the work I've been doing on economic models of long-term storage. CNI recorded the talk and I'm expecting them to post the video and the slides. Much of the talk expanded on the talk I gave at the Library of Congress Storage Workshop. The new part was that I managed to remove the assumption that storage prices could never go up, so I was able to model the effect of spikes in storage costs, such as those caused by the floods in Thailand.. Below the fold is the graph.

Progress on the Economic Model of Storage

I've been working more on the economic model of long-term storage. As an exercise, I tried to model the effect on the long-term cost storage on disk of the current floods in Thailand. The more I work on this model, the more complex the whole problem of predicting the cost of long-term storage becomes. This time, what emerged is that, despite my skepticism about Kryder's Law, in a totally non-obvious way I had wired in to the model the assumption that disk prices could never rise! So when I tried to model the current rise in disk prices, things went very wrong. So, until I get this fixed, the best I can do is to model a pause of a varying number of years before disk prices resume their Kryder's Law decrease.

For this simulation, I assume that interest rates reflect the history of the last 20 years, that the service life of disks is 4 years, that the planning horizon is 7 years, that the disk cost is 2/3 of the 3-year cost of ownership, and that the initial cost of the unit of storage is $100. The graph plots the endowment required to have a 98% probability of surviving 100 years (z-axis) against the length of the initial pause in disk cost decrease in years (y-axis), and the percentage annual decrease in disk cost thereafter (x-axis).

As expected, the faster the disk price drops and the shorter the pause before it does, the lower the endowment needed. In this simulation the endowment needed ranges from 4.2 to 17.6 times the initial cost of storage, but these numbers should be taken with a grain of salt. It is early days and the model has many known deficiencies.

PLoS Is Not As Lucrative As Elsevier

David Crotty of Oxford University Press made the headline-grabbing charge that PLoS will this year be more profitable than Elsevier. I responded skeptically in comments, and Kent Anderson, a society publisher, joined in to support David. Comments appear to have closed on this post, but I have more to say. Below the fold I present a more complete version of my analysis and respond to David's objections.

What Problems Does Open Access Solve?

The library at the University of British Columbia invited me to speak during their Open Access Week event. Thinking about the discussions at the recent Dagstuhl workshop I thought it would be appropriate to review the problems with research communication and ask to what extent open access can help solve them. Below the fold is an edited text of the talk with links to the sources.

Seminar at UC Santa Cruz

I gave a seminar in Ethan Miller's CMPS290S course at UC Santa Cruz. It was a mash-up of my blog posts on Paying For Long-Term Storage and Modeling the Economics of Long-Term Storage. The links to the sources are all in those posts, except for Wide-Body: The Triumph of the 747, which I used to illustrate the importance for successful engineering of understanding the market for your product.

Do Digital Signatures Assure Long-Term Integrity?

Duane Dunston has posted a long description of the use of digital signatures to assure the integrity of preserved digital documents. I agree that the maintaining the integrity of preserved documents is important. I agree that digital signatures are very useful. For example, the fact the GPO is signing government documents is important and valuable. It provides evidence that the document contains information the federal government currently wants you to believe. Similarly, the suggestion by Eric Hellman to use signatures to verify that Creative Commons licenses have been properly applied.

However, caution is needed when applying digital signatures to the problem of maintaining the integrity of digital documents in the long term. Details below the fold.