EC2's IO performance depends on type of instance storage (ephemeral or EBS) used and instance size. The m2.* instance sizes with EBS actually outperformed racks

EC2's IO performance depends on type of instance storage (ephemeral or EBS) used and instance size. The m2.* instance sizes with EBS actually outperformed rackspace in our tests, whereas m1.small performed about 2/3 slower than Rackspace.