You've learned how to store data, but what happens if there's a failure? Protecting your database involves planning for availability (keeping it online) and durability (not losing data). Let's look at the strategies AWS provides.

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What's the business impact if an e-commerce website's database is down for an hour?

Database backups are the first line of defense. Amazon RDS automatically creates daily backups of your database. These backups, along with transaction logs, allow for point-in-time recovery.

This means you can restore your database to any specific second within your retention period, not just to the time of the daily backup.

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Why is restoring to a specific time better than just restoring yesterday's backup?

Let's define two critical terms. Recovery Point Objective (RPO) is the maximum acceptable amount of time since the last data recovery point. Essentially, it's how much data you can afford to lose.

If your last backup was at midnight, and a failure happens at 10 AM, your potential data loss is 10 hours.

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How much data loss would be acceptable for your favorite app or website?

Recovery Time Objective (RTO) is the maximum acceptable amount of time it takes to bring your application back online after a failure. Restoring a large database from a backup might take hours, during which your application is down.

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For a critical application, is an RTO of several hours acceptable?

To improve RTO, RDS offers Multi-AZ deployments. This feature creates a synchronized, standby copy of your database in a different Availability Zone. If your primary database fails, RDS automatically fails over to the standby.