RDS
A Database service with a choice of common database technologies as well as Aurora.
Under the covers RDS runs on EC2 with EBS. When configuring you have a choice of the types of compute instance used:
- Standard: general purpose
- Memory Optimised: for memory intensive applications
- Burstable Performance: a baseline which can burst to max CPU usage
and the type of storage: - General Purpose (SSD)
- Provisioned IOPS (SSD)
- Magnetic Storage (not recommended)
Redundancy
By default the Relation Database Service deploys one instance into a subnet with an AZ, but you can get redundancy using RDS Multi-AZ configuration.
RDS Multi-AZ
A redundant database with two instances in different AZs, a
- Primary where applications can make queries.
- Secondary where data is replicated which acts as a standby.
RDS automatically triggers a failover if issues occur with an AZ. DNS is used to determine which instance is primary and where to direct traffic.
Backups
Data can be backed up using automatic backups (on by default) or manual snapshots so that you can restore to a point in time.
Automatic snapshots only last for 35 days, to keep backups longer use manual snapshots.