RDS, Aurora & ElastiCache Flashcards
What is RDS?
Relational database service
What dies RDS manged?
- Automated provisioning, OS patching
- Continuous backups and restore to specific timestamp (Point in Time Restore)!
- Monitoring dashboards
- Read replicas for improved read performance
- Multi AZ setup for DR (Disaster Recovery)
- Maintenance windows for upgrades
- Scaling capability (vertical and horizontal)
- Storage backed by EBS (gp2 or io1)
What you can’t do on RDS?
You cannot SSH into your instance
Which backups does RDS have?
Full daily backup
Logs - every 5 min.
How long are the backups kept? Which point in time can you go back to?
Ability to restore to any point in time (from 5 minutes ago or seven days ago)
7 days retention - can increase to 35
What features do DB snapshots have?
Manually triggered
Kept of as long as you want
What features do RDS storage auto scaling have?
Helps increase storage dynamically
increase automatically when DB run out of free space - avoid manually scaling
What are the conditions for RDS to start auto scaling?
- Free storage is less than 10% of allocated storage
- Low-storage lasts at least 5 min
- 6 hours have passed since last modification
What kinds of applications can benefit from RDS auto scaling?
Useful for applications with unpredictable workloads
What are the features of RDS read replicas for read scalability?
- Up to 5 read replicas: (1)Within AZ (2)Cross AZ (3) Cross region.
- ASYNC - reads are eventually consistent.
- Promoted to their won DB.
- Must update the connection string to leverage read replicas
How do the network costs for RDS read replications in various AZs and the same region differ?
For RDS read replicas within the same region - you don’t need to pay that fee.
What are the benefits of RDS Multi AZ?
- SYNC replication
- One DNS name – automatic app failover to standby.
- Increase availability
- Failover in case of loss of AZ, loss of network, instance or storage failure.
- No manual intervention in apps.
- Not used for scaling
- Multi-AZ replication is free.
- Note:The Read Replicas be setup as Multi AZ for Disaster Recovery (DR)
Can the Read Replicas be setup as Multi AZ for Disaster Recovery (DR)?
Yes!
Hod do we make a RDS goes from single AZ to multi AZ?
- Click “modify” for the database.
- Zero downtime operation (no need to stop the DB)
What append internally when you go from single AZ to multi AZ?
- A snapshot is taken
- A new DB is restored from the snapshot in a new AZ
- Synchronization is established between the two databases