6.65 RDS, AURORA AND ELASTICACHE Services

This section introduces RDS, Aurora and ElastiCache. RDS stands for Relational Database Service: a managed database service for transactional SQL workloads. RDS lets you create databases in the cloud that AWS provisions, patches, backs up and monitors for you. Supported engines are PostgreSQL, MySQL, MariaDB (based on MySQL), Oracle, Microsoft SQL Server, and Amazon Aurora — AWS's proprietary engine covered in a dedicated section.

Why use RDS rather than installing MySQL on EC2

  • Managed service: automatic provisioning, OS and engine patching, maintenance windows.
  • Continuous backups with point-in-time restore — go back to any second within the retention window.
  • Dashboard with monitoring, metrics and supervision.
  • Read replicas to scale reads horizontally.
  • Multi-AZ deployment for high availability and disaster recovery (DR).
  • Vertical scaling (resize instance) and horizontal scaling (read replicas).
  • Storage on EBS (gp2 or io1).
  • No SSH access to the database host — fully managed.

Backups are enabled by default: a full snapshot is taken once per day during the maintenance window, and transaction logs are uploaded every five minutes. You can restore to any point in time between database creation and roughly five minutes ago. Default retention is 7 days, configurable up to 35 days.

Database snapshots are user-triggered and survive indefinitely — useful to keep a known state for compliance, before a migration, or for very long-term retention. The next lessons will explore RDS read replicas, multi-AZ deployments, security and encryption, then move on to Aurora and ElastiCache patterns.