Expanding the Cloud: The Amazon RDS

Excellent notes on various Data base systems available on Amazon Cloud and explanation of key constraints that must be kept in mind while deciding on a system for a given application. Note that there is no one system that fits the best for all applications. Architects must pick the choice that is right in a given context.

Excerpts from the article that highlight various options available : Amazon S3 (Simple Storage Service), Amazon SimpleDB and Amazon RDS

Early on already the distinction was made between key-values storage systems and structured data management. Key-Value storage systems play a very important role in the Amazon architecture and this has ultimately led to the creation of the Amazon Simple Storage Service (Amazon S3). Amazon S3 addresses the need for a highly scalable and reliable Key-Value data storage system while shielding customers from all the complexities such as geo-replication, capacity planning, and performance management at high scale.

Structured data management systems are traditionally served by relational databases but these sophisticated systems have their limitations, especially when it comes to scale and reliability. Often they also require tremendous expertise to operate efficiently and reliably especially when scaling up. Of course, a significant portion of the structured data world does not require RDBMS features such as complex transactions and relations, and can be served by a simpler, much more agile system. Such a simple structured storage system for example does not require the use of a rigid schema and can allow attributes and indexes to be adapted on the fly. This system has led to the creation of Amazon SimpleDB where its customers get the benefits of such a simple scalable structured storage system without having to worry about replication, backups, buffer cache optimizations, databases resizing, etc

There are a several applications and services that do need the feature richness of an RDBMS. Until now they were served through the use of the Relational Database AMIs that are available for Amazon EC2. These AMIs can be launched to create a compute instance with database technologies such as Vertica, Oracle, DB2, SQL Server, Sybase, and PostgreSQL. These RDBMS are best used in concert with the Amazon Elastic Block Store (EBS) to create a scalable and reliable storage volume that can be used for persisting the databases.

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For these customers who require a relational database but do not have a need to exert complete administrative control over their database server, there is now another option: the Amazon Relational Database Service (Amazon RDS)."

Source : Expanding the Cloud: The Amazon Relational Database Service (RDS)