section 9 RDS

• RDS


  Relational Database Service
• RDS is a managed database service for databases that use SQL as a query language
• SQL


  A structured language to query databases
• Types of database engines managed by AWS

  • PostgreSQL
  • MySQL
  • MariaDB
  • Oracle
  • Microsoft SQL Server
  • IBM DB2
  • Aurora
• Aurora is a proprietary database from AWS
• Benefits of using RDS

  • Fully automated provisioning
  • Automated operating system patching
  • Continuous backups
  • Point in Time Restore
  • Monitoring dashboards
  • Read replicas
  • Multi AZ setup
  • Maintenance windows for upgrades
  • Scaling capabilities
• Point in Time Restore


  Ability to restore to a specific timestamp
• Read replicas


  Used to improve read performance
• Multi AZ


  Helpful for disaster recovery
• RDS Storage Auto Scaling


  Automatically scales storage when certain conditions are met
• RDS Storage Auto Scaling detects when storage is running low and scales automatically
• RDS Storage Auto Scaling conditions

  1. Set maximum storage threshold

  2. Free storage less than 10%

  3. Low-storage lasts more than 5 minutes

  4. 6 hours since last modification
• RDS Storage Auto Scaling supports all database engines for RDS
• Users cannot SSH into RDS instances
• AWS provides a managed service, so users do not have access to the underlying EC2 instance
• RDS aims to avoid manual scaling of database storage
• Going into the exam is going to be extremely important to understand the difference between RDS Read Replicas and Multi AZ
• Read Replicas


  Help you to scale your reads
• Creating Read Replicas


  1. Create up to 15 Read Replicas

  2. Can be within the same availability zone

  3. Cross availability zone

  4. Cross region
• Asynchronous replication


  • Reads are eventually consistent
• Read Replicas can be promoted to their own database
• Read Replicas are only for SELECT type of statements
• INSERT, UPDATE or DELETE cannot be used with Read Replicas
• There is a cost when data goes from one availability zone to another
• RDS Read Replica is a managed service
• Read Replica within the same region

  No replication fee
• Cross region replica


  Incurs a replication fee
• Multi AZ


  Mainly used for Disaster Recovery
• Multi AZ setup


  1. Application performs reads and writes to Master

  2. Synchronous replication to standby instance

  3. Automatic failover to standby database
• Multi AZ provides one DNS name for the application
• Standby database is just for standby
• Read Replicas can be set up as Multi AZ for Disaster Recovery
• Going from Single AZ to Multi AZ is a zero downtime operation
• Transitioning to Multi AZ

  1. Click on modify for the database

  2. Enable Multi AZ

  3. Snapshot taken of main database

  4. Snapshot restored into new standby database

  5. Synchronization established between databases
• The standby database will catch up to the main RDS database
• RDS Custom


  A service that allows access to the underlying operating system and customization for databases
• RDS Custom


  • Access to OS
  • Database customization
• Database types for RDS Custom

  • Oracle
  • Microsoft SQL Server
• With RDS, we don't have access to any underlying operating system or customization
• With RDS, we still get all the benefits of automated setup, operations, and scaling of the database in AWS