RDS - davidkhala/aws-collection GitHub Wiki

RDS (classic)

Deployment

Default: Single DB provision on EC2

Reliability Architecture

  • you need to enable the Multi-AZ feature on your RDS instance and replicate it synchronously to a standby replica in another Availability Zone. (up to only 1 sync replica)
  • put up 1 Read-only async replica in another Availability Zone
  • Storage Auto Scaling, up to 64 TB (SQL server 16TB)
  • Cluster Endpoints
    • RDS does not provide a load balancer for read replicas.
    • There is a cluster endpoint which you use for your write queries. During a failover, RDS routes this endpoint to the new master

Aurora

Compared to classic RDS

  • Up to 15 replica
  • 2 data flow paths between replicas to ensure replica lag is small and consistent over time
    • Aurora writes logs directly to the storage without keeping log buffers. (shared storage volume)
    • The replication to the replicas is asynchronous and for only cached data. (asynchronous cache replication)
  • Aurora scales faster because
    • A new replica can reuse the shared storage volume, can serve queries almost immediately. It doesn’t have to wait to replicate data from the other nodes.
    • Aurora does some asynchronous cache replication between nodes, but nothing synchronous. This reduces the inter-node I/O

serverless v2

Provision time over 8 minutes image

No public access:

  • You can't give an Amazon Aurora Serverless DB cluster a public IP address.
  • You can access an Aurora Serverless DB cluster only from within a virtual private cloud (VPC)