Database Backups, Multi-AZ Flashcards
What are the two types of database backups?
Automated
Database
Automated Backup Overview
let you recover your database to any point in time within a retention period of 1-35 days.
Take a full daily snapshot and stores transaction logs through the day.
Recovery will choose the most recent daily backup, then apply transaction logs to the point in time you want to recover to
Are automated backups enabled by default?
How much storage do you get for free?
Yes
you get free space equal to the size of your database
Backups deleted when RDS instance deleted
What happens to storage I/O during your backup window (for automated backups)
storage i/o may be suspended while data is backed up, causing latency
Snapshot backup overview
Database snapshots are performed manually
they’re stored even after original RDS instance is deleted (unlike automated backups)
When you restore an automatic or manual backup, is the restored version of the database a new RDS instanc with a new endpoint?
Yes
What databases support encryption at rest?
MySQL SQL Server Oracle PostgreSQL MariaDB
Are backups, snapshots and read replicas encrypted, once the database is encrypted?
yes
Can you encrypt an existing DB instance?
No
You would have to create a new DB instance with encryption enabled and migrate your data to it
What is the purpose of multi-AZ in Amazon RDS?
It’s for disaster recovery only
Not for performance
What databases does multi-AZ support?
SQL, MySQL, Oracle, PostgreSQL, MariaDB
Aurora has its own multi-AZ functionality
What’s the purpose of read replicas?
Scaling
Performance improvements for read-heavy workloads
Can you have read replicas, of read replicas?
Yes
But latency increases
How many read replica copies of your main database can you have?
5
What databases support read-replicas?
My SQL, PostgreSQL, MariaDB
Do you need automatic backups enabled to deploy a read replica?
Yes
Does each read replica get its own DNS endpoint?
Yes
Can you have read replicas that are multi-AZ?
No
Can you have read replicas of a multi-AZ source database?
Yes
What databases support a read replica in a second region?
Only MySQL, MariaDB
DynamoDB vs RDS
DynamoDB has push-button scaling, you can scale on the fly with no downtime
RDS requires a bigger instance size or adding a read replica
