In the context of AWS databases, how do the following disaster recovery strategies differ from one another:
When should we choose one over the others?
Why do we need so many different options when one will suffice?
Should we try to use all of them?
One key difference between a manual snapshot and an automatic backup is that a snapshot doesn't expire, whereas an automatic backup are usually stored for a maximum of 35 days.
When you enable automated backups for your AWS database, AWS takes periodic backups of your database and stores them in Amazon S3. These backups serve as the starting point for PITR. AWS keeps transaction logs in S3 for up to 35 days, allowing you to perform point-in-time recovery (PITR) to any point within that timeframe.
When you initiate a PITR restore operation, AWS uses the selected backup and the transaction log to restore your database to the desired point in time. AWS first restores the backup and then applies the relevant transactions from the transaction log to the restored backup. This process brings the database to the desired point in time, allowing you to recover your data as it existed at that time.
Aurora Backtrack allows you to easily undo unintended or incorrect changes to your database by rolling back the database to a specific point in time without needing to restore from a backup. This allows fast rollbacks without the need to create a new database instance. However, Aurora Backtrack has a maximum backtrack window of 72 hours, which means you can only roll back your database to any point in time within the last 72 hours. This is because Aurora Backtrack uses the transaction log to roll back changes, and transaction logs are only kept for 72 hours.