Read Replica

Up to 15 read replicas
Within AZ, Cross AZ or Cross Region
Replication is Async, reads are eventually consistent
Replica can be promoted to their own db. I will keep living with its own life cycle later.
App need to update connection string to connect new one
For reporting application we can separately read read-replica only
Network cost
Within same region no fee for replication
If spread across different regions, have to pay fee

Multi AZ(Disaster Recovery)

SYNC replication, One DNS name automatic app failover to standby
Increase availability

Single AZ to Multi AZ

Zero downtime operation
How it work under the hood

• Take snapshot, create new standby az
• Synchronization started

RDS custom

Managed MSQL server, oracle
Have access to underlying os and db

• So can configure settings
• Install patches
• Can access underlying instance
• Deactivate automation mode to customize(better to take DB snapshot before)
  RDS vs RDS custom
  RDS: AWS manage
  RDS custom: full access to underlying database and OS

Backups

Automated backups

Daily full backup at the backup windows
Transitions logs are backup every 5 minutes
Ability to restore any point in time (from oldest backup up to 5 minutes)
1 to 35 days retentions, set 0 to disable backup

Manual DB snapshots

User manually take snapshot of aurora
Retention can be as long as the user wants
Tip: to save cost for stopped database, take snapshot and delete original database. Can use snapshot to restore data at anytime.

Restore

From s3
Backup on premise database
Store backup on s3
Restore that backup from s3 on rdb running mysql