The Storage Service
When you are ready for higher performance and scalability, you will integrate a storage service. A storage 'service' can be anything from a SQL database, to a key/value store, to a true service like Amazon's DynamoDB. You will still use the peer and client libraries described above, but will configure it and the transactor to use one of the external storage protocols. The currently supported protocols are ddb backed by DynamoDB, cass backed by Cassandra, and sql backed by a SQL database (like PostgreSQL).
When using EC2 you can use our prebuilt Amazon AMI transactor. You will need an Amazon AWS account. Our tools will help you configure users, security groups, auto-scaling, metrics, cloud-formation and other details of AWS.
When using Cassandra or SQL, you will need to stand up the storage system/server yourself, with scripts we provide to help you with e.g. installing the schemas Datomic requires.
Integrated memcached Support
Another feature of the Datomic is optional memcached support. Simply configure the transactor and peers with your memcached servers and they will be transparently utilized as a distributed backing cache for data segments.
You can move an application from the memory database, to dev mode, to a storage-service based configuration with a switch of the connection string on the peers and a properties file on the transactor. All are fully API-compatible. You can move databases between storages with the backup/restore facilities.