Redshift is a petabyte-scale data warehousing solution. It’s a column-based database designed for analytical workloads. Generally, a relational store like RDS would be used for OLTP workloads (e.g., queries, inserts, updates, and deletes), and Redshift would be used for OLAP (e.g., retrieval and analytics). Multiple databases become source data to be injected into a data warehouse solution such as Redshift.
Data can be loaded from S3 and unloaded to S3. Additionally, backups can be performed to S3, and various AWS services such as Kinesis can inject data into Redshift.