Decide on RDS Aurora DB Cluster Requirements
Problem
Requirements for Amazon Aurora DB clusters deployed to each active compute environment need to be outlined before an Amazon Aurora component is configured and deployed
Context
Amazon RDS provides MySQL and PostgreSQL-compatible relational databases that are built for the cloud with greater performance and availability at 1/10th the cost of traditional enterprise databases with the simplicity and cost-effectiveness of open source databases. RDS Aurora features a distributed, fault-tolerant, self-healing storage system that auto-scales up to 128TB per database instance. It delivers high performance and availability with up to 15 low-latency read replicas, point-in-time recovery, continuous backup to Amazon S3, and replication across three Availability Zones.
Amazon Aurora DB clusters (See: Decide on RDS Technology and Architecture)
Known Limitations
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Max of 15 Read Replicas (we had a customer decline RDS Aurora based on this limitation)
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Point-in-time recovery (PITR) is not yet supportedRDS Aurora now supports PITR. https://aws.amazon.com/blogs/storage/point-in-time-recovery-and-continuous-backup-for-amazon-rds-with-aws-backup/ -
Cannot be launched on public subnets
Considered Options
Create a standardized Aurora DB cluster based on the current use case:
Current Infrastructure Requirements
RDS Aurora Replication
RDS aurora replication happens at the filesystem layer versus the conventional database layer. It’s actually a shared filesystem. Hitting the read replicas hard can still impact the masters since they are using the shared filesystem.
Because the cluster volume is shared among all DB instances in your DB cluster, minimal additional work is required to replicate a copy of the data for each Aurora Replica. https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Replication.html
RDS Serverless v1 vs v2
Using serverless could be more costly that using regular RDS aurora due to not having enough options for CPU.
Serverless v1 offers more granular scaling units. Only operating in a single availability zone. Serverless v1 only supports up to v10 of Postgres (v10 will be sunset by Postgres on November 10, 2022).
Serverless v2 offers multi-AZ, so that DB subnets can be across multiple availability zones. Supports Postgres 12+.
https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-serverless-v2.upgrade.html
Future Aurora DB Cluster Requirements
Because the RDS Service documentation on Aurora DB clusters recommends deploying at least one additional Aurora DB cluster instance to an Availability Zone other than where the primary instance is located in order to ensure High Availability, and since 3 AZs are used by the primary AWS region, it is recommended that 3 instances are deployed per Aurora DB cluster when High Availability is needed.
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Explain how many instances exist in the cluster (or per region, if this is a global cluster)
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Explain whether the cluster is global or regional, and reference Decide on RDS Technology and Architecture
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Explain how many secondary DB clusters should exist, if this is a global cluster
Lastly, database storage encryption, deletion protection and cloudwatch logs exports should be enabled as a best practice.
This, in addition to any of the requirements outlined in v1 Infrastructure Requirements, should be captured in the following table.
Setting
- Aurora DB cluster Engine
- Aurora DB cluster Instance Family
Number of Aurora DB cluster Instances: 1 for all environments except for prod, 3 for prod (or 2 when < 3 AZs are available)
- Regional or Global DB Cluster
- Security-related settings
- Storage Encryption enabled
- yes
Other Considerations
Consequences
Create an Aurora DB Cluster component and tune it to the outlined requirements.