7-5 Backup and Recovery Strategies Explained

Key Concepts

• Full Backup
• Incremental Backup
• Differential Backup
• Backup Retention Policy
• Recovery Point Objective (RPO)
• Recovery Time Objective (RTO)
• Disaster Recovery Plan

Full Backup

A full backup is a complete copy of all data in the database. It includes all files, tables, and configurations. Full backups are typically performed less frequently because they are time-consuming and require significant storage space.

Example: Performing a full backup of a "Customers" table every Sunday ensures that all customer data is backed up weekly.

Analogies: Think of a full backup as taking a photograph of an entire room. It captures everything in the room at a specific moment.

Incremental Backup

An incremental backup only backs up the data that has changed since the last backup. This includes both full and incremental backups. Incremental backups are faster and require less storage space but can be complex to restore.

Example: Performing an incremental backup of the "Orders" table every day, starting from the last full backup, ensures that only new orders are backed up.

Analogies: Think of an incremental backup as adding new pages to a book. Each new page is added to the existing book, but you only need to store the new pages.

Differential Backup

A differential backup captures all changes made since the last full backup. Unlike incremental backups, differential backups are cumulative but faster to restore because they only require the last full backup and the most recent differential backup.

Example: Performing a differential backup of the "Products" table every day, starting from the last full backup, ensures that all changes since the last full backup are captured.

Analogies: Think of a differential backup as adding new chapters to a book. Each new chapter includes all changes since the last full book, but you only need the last full book and the new chapters to restore the entire book.

Backup Retention Policy

A backup retention policy defines how long backups are kept and when they are deleted. It ensures that backups are available for the required period while managing storage space efficiently.

Example: Keeping full backups for 30 days, incremental backups for 7 days, and differential backups for 14 days ensures that recent backups are available while older backups are deleted.

Analogies: Think of a backup retention policy as a library's policy for keeping books. Some books are kept permanently, while others are removed after a certain period.

Recovery Point Objective (RPO)

RPO is the maximum acceptable amount of data loss measured in time. It defines the point in time to which data must be recovered after a disaster. A lower RPO indicates less data loss but requires more frequent backups.

Example: An RPO of 1 hour means that the database must be restored to a state no older than 1 hour before the disaster occurred.

Analogies: Think of RPO as the maximum amount of time you can afford to lose when recovering from a disaster. For example, if you can only afford to lose 1 hour of work, your RPO is 1 hour.

Recovery Time Objective (RTO)

RTO is the maximum acceptable downtime for a system after a disaster. It defines the time within which the system must be restored to normal operations. A lower RTO indicates faster recovery but may require more resources.

Example: An RTO of 2 hours means that the database must be fully operational within 2 hours of a disaster.

Analogies: Think of RTO as the maximum amount of time your business can afford to be offline. For example, if you can only afford to be offline for 2 hours, your RTO is 2 hours.

Disaster Recovery Plan

A disaster recovery plan (DRP) is a documented, structured approach with instructions for responding to unplanned incidents. It includes procedures for backing up data, restoring systems, and ensuring business continuity.

Example: A DRP might include steps for performing regular backups, testing backup restoration, and setting up a secondary site for failover.

Analogies: Think of a DRP as a fire escape plan for a building. It outlines the steps to take in case of an emergency to ensure everyone's safety.

Conclusion

Backup and recovery strategies are essential for ensuring data integrity and business continuity. By understanding and implementing full, incremental, and differential backups, along with appropriate retention policies, RPO, RTO, and a comprehensive disaster recovery plan, you can protect your database from data loss and minimize downtime in the event of a disaster.