From the Amazon ☞ Migrating your Existing Applications to the AWS Cloud paper (PDF):
- What are the different storage options available in the cloud today?
- What are the different RDBMS (commercial and open source) options available in the cloud today?
- What is my data segmentation strategy? What trade-offs do I have to make?
- How much effort (in terms new development, one-off scripts) is required to migrate all my data to the cloud?
When choosing the appropriate storage option, one size does not fit all (nb: my emphasis). There are several dimensions that you might have to consider so that your application can scale to your needs appropriately with minimal effort. You have to make the right tradeoffs among various dimensions - cost, durability, query-ability, availability, latency, performance (response time), relational (SQL joins), size of object stored (large, small), accessibility, read heavy vs. write heavy, update frequency, cache-ability, consistency (strict, eventual) and transience (short-lived).
Just replace the words “cloud” and “AWS” with NoSQL database and you get a good base for your migration plan.