RDS

Fully-Managed SQL Database Engines as a Service on AWS

Essentials

• Managed Relational Database Service

  • No access to underlying OS

  • Connect to the RDS database server in the same way you connect to traditional on-premise DB instances (MySQL command line)

  • Provision/Resize on demand for scaling

  • Mutli-AZ deployments for backup and high availability

  • Read Replicas to help offload hits on your primary database

  • Often OLTP databases

• Supported DBs

  • MySQL

  • MariaDB

  • PostgreSQL

  • Oracle

  • MS SQL

  • Aurora

• Benefits of RDS vs Your Own:

  • Automatic minor updates

  • Automatic backups (point-in-time snapshots)

  • Server/Platform managed by AWS (PaaS)

  • Multi-AZ in a single click

  • Automatic recovery in the event of a failover

Backups

• AWS Provides automated point-in-time backups against the RDS DB instance

• Deleted once the database is deleted and cannot be recovered

• Maximum retention is 35

• Manual snapshots retained as long as you want

• Snapshots can be copied to other regions for Disaster Recovery purposes

• RDS Encryption - snapshots are automatically encrypted

Read Replicas

• Read replicas are asynchronous copies of the primary database that are used for read only purposes (only allow "read connections").

• When you write new data to the primary database, AWS copies it for you to the read replica

• You can create, and have multiple read replicas for a primary DB

• Cross-region read replicas are supported

• MySQL, MariaDB, PostgreSQL, and Aurora currently support read replicas.

• You can monitor replication lag using CloudWatch

Multi-AZ Failover:

• Synchronously replicates data to a backup DB instance located in another availability zone (but in the same region)

• In the event of:

  • Service outage in an AZ

  • Primary DB instance failure

  • Instance server type is changed

  • Manual failover initiated

  • Updating software versions

  • AWS will automatically switch the DNS record from the primary instance to the stand-by instance

• RDS backups are taken against the stand-by instance to reduce I/O freezes and slow down IF multi-az is enabled

• In order for multi-az to work, your primary database instance must be launched into a "subnet group"

Aurora

• AWS home-grown relational DB forked from and fully compatible with MySQL and PostgreSQL

  • 5x better performance than MySQL, 3x faster than PostgreSQL, lower price point as well

  • Features:

    • Continuous Backup

    • Up to 15 Read Replicas across 3 AZs

    • Replication Lag of Single digit milliseconds

    • Backtrack in Seconds

    • Multi-Master Option

  • Aurora Serverless

    • Autoscaling

    • No management of instances/clusters

    • Scales to Zero

    • Pay-as-you-go: (ACUs, Storage, I/O)