Rackspace Cloud's offering is nice, though, in that you get guaranteed, durable storage with each instance. Their EBS-like offering will allow people to supple

Rackspace Cloud's offering is nice, though, in that you get guaranteed, durable storage with each instance. Their EBS-like offering will allow people to supplement that storage if what they have in-machine isn't sufficient, but users will be able to decide for themselves about the speed and reliability tradeoffs around what goes where (unlike with Amazon, where everything that needs to be durable has to go on EBS). The resulting system will be both more flexible, and, I would guess, more performant, if only because I would expect lighter load given that many users won't need to use this offering at all. Separately, it also seems that Amazon's architecture under EBS has at least some per-AZ single points of failure, such that certain classes of issues can take down storage for a whole (or at least large parts of an) AZ. There doesn't seem to be any a priori reason that this needs to be the case; I could imagine an EBS-like system that would have storage per rack, say, which would appear similar from the user's perspective except that it might perform better and would be unlikely to disable all of their instances at once if it failed. No idea how Rackspace's implementation works, but I doubt all EBS-like solutions are created equal in terms of reliability.