[mike_hearn]

I think the details of IO are already abstracted pretty well, it's a topic that's had a lot of effort put into it. The remaining things you have to think about are pretty fundamental and not fundamentally technical in nature, like:

1. Price

2. Brand of whoever is providing the storage (matters because it's a proxy for lots of other details)

3. General physical location

Once you made those decisions services like S3 abstract the rest. There are tools that let you access these via FUSE (in which case client protocols don't matter).