RDS + Aurora + Elasticache Flashcards
RDS
Relational Database Service
Managed DB Service that uses SQL as a query language
RDS Storage AUto Scaling
Detects when you run out of free database storage, scales automatically
You have to set Maximum Storage Threshold
Useful for applications with unpredictable workloads.
RDS Read Replicas
Application performs reads and writes to replicas Database instance, which sends read data to application.
Up to 15 read replicas
within AZ, cross AZ or cross Region.
Replication is asynchronous so reads are eventually consistent.
Replicas can be promoted to their own DB
Application must update the connection string to leverage read replicas.
Use Case: you have production database taking on normal load, but you want to run a reporting application. you create read replica to run the new workload there.
RDS Read Replicas- Network Cost
RDS read replicas within same region, you don’t pay that replication fee.
RDS
Multi AZ
For disaster recovery
Sync Replication
One DNS name- automatic app failover to standby
Increases availability
Failover in case of loss of AZ, loss of network, instance or storage failure.
Not used for scaling.
Read replicas can be setup as Multi AZ for disaster recovery.
RDS from single-az to multi-az
zero downtime operation ( no need to stop DB)
just click on “modify” for the database and enable multi-AZ.