AWS Solution Architect Associate (SAAC02) Review Material – RDS

General

• A managed Relational Data Service (RDS)
• Supports the following databases:
  • MySQL
  • MariaDB
  • PostgreSQL
  • SQL Server
  • Oracle
  • Aurora
  • Aurora Serverless
• The following does NOT apply to Aurora Serverless:
  • All has to provision a host instance to run the database. However, user will have no access to the instance.
  • The host will have a corresponding ENI so the database has to be placed in an subnet, AZ and VPC.
  • When provisioning the database, users has to:
    • select the instance class/size
    • select the storage type/size, except for Aurora because it does not require to provision a storage.
  • Storage can now be autoscaled (except for Aurora)
  • Backup is enabled by default. Backup retention can be from 0 – 35 days. Default to 7 days.
  • Automated backups are limited to a single AWS Region while manual snapshots and Read Replicas are supported across multiple Regions
  • Encryption is enabled by default.
  • Can enable enhanced monitoring – metrics in real time for the operating system (OS) that the DB instance runs on
  • Can enable deletion protection.

Read Replicas

• Read Replicas are copies of the Master. Replication is asynchronous.
• Support read connections. However, clients must be aware it is only eventually consistent.
• Aurora Serverless does not have Read Replicas.
• Aurora’s maximum number of replicas is 15; the rest is 5.
• Can be placed on the same AZ, across AZ or across regions.
• There’s a fee when replicating across regions.
• Can become a Master but promotion needs to be done manually. So if the Master fails, Replicas do not become a Master automatically.
• Used for scaling.

Multi-AZ

• Creates copies of the Master database synchronously to a Standby database.
• Non-Aurora: Only one is master. The copies do not support read or write connections.
• Aurora: Supports multi-master
• Automatically promoted to Master when the Master fails.
• Used for high availability.
• The number of copies will depend on the number of subnets in the Subnet Group.

Security

• At Rest Encryption:
  • Must be set upon database creation.
  • If the Master is not encrypted, the replicas and their snapshots are also not encrypted.
  • Can’t restore the unencrypted backup to an encrypted database.
  • But you can encrypt an unencrypted snapshot and use that to restore to an encrypted database.
  • Use KMS to store encryption keys.
  • If you copy a snapshot from one region to another you must use that region’s KMS key.
• In-Flight Encryption
  • Use SSL/TLS to encrypt connections to databases. However, each database has its own process of implementing an SSL/TLS connection.
  • PostgreSQL and MySQL can enforce SSL/TLS connection.
• IAM-based:
  • Log in to the database using a token, not a username/password.
  • Only available in PostgreSQL, MySQL and MariaDB
  • To use this feature, the resource with the given role must call an API to get a temporary token (which expires in 15 mins).
  • Then it will use that token to log in to the database.

Aurora

• MySQL and PostgreSQL compatible. It means any clients using these databases’ APIs will work on Aurora.
• 5x faster than MySQL and 3x faster than PostgreSQL
• Storage does not have to be provisioned. It will scale automatically by 10GB increment up to 128TB.
• Faster failover.
• Can have 15 replicas. Can set up autoscaling on Read Replicas.
• Read Replicas can be set up across regions.
• Global Setup
  • 1 Primary region
  • Up to 5 secondary regions. Each region can have 16 Read Replicas.
  • Any region can be promoted to Primary when disaster strikes in the Primary region.
• 6 copies of data across AZ.
  • Only requires 4 copies to write.
  • Only requires 3 copies to read.
• Endpoints:
  • Writer endpoints for writing.
  • Reader endpoints for reading. Distributes reads to all replicas.
  • Custom endpoints to point to selected Read Replicas.
• The standard setup is to have only one writer node. But can be set up for multi-master i.e. multiple writer nodes
• Autoscaling:
  • Add more replicas

Aurora Serverless

• Instances are automatically created and auto-scaled. No need to provision instances and storage.
• Pay per second
• Good for the unpredictable and intermittent workload.