Adrian Cockcroft has a great explanation of the impact of multi-tenancy on cloud storage performance. The connection with NoSQL databases is not necessarily in the Amazon EBS and SSD Price, Performance, QoS comparison, but:
If you ever see public benchmarks of AWS that only use m1.small, they are useless, it shows that the people running the benchmark either didn’t know what they were doing or are deliberately trying to make some other system look better. You cannot expect to get consistent measurements of a system that has a very high probability of multi-tenant interference.
Original title and link: Multi-tenancy and Cloud Storage Performance (NoSQL databases © myNoSQL)