you probably also don't want to run a DB on non-raid disk. I believe the ec2 instances have non-mirrored disk, I mean, if you are not using ebs. (if you don't care about the data, use something with more ram, and mount the disk async. Ram is going to be faster than disk, always.)
I'm just pointing out that you don't want to run your db on non-redundant disk. Really, I think in-ram, redundant databases like MySQL cluster are more suited to the 'cloud' - especially as you can get cheap ram.
Just looking at the bonnie results, ebs wasn't that far off everything else in terms of sequential access.
