# Disaster recovery

> The plan for getting systems and data back after a major failure.

- Level: Intermediate
- Topics: Cloud
- URL: https://tidbit.legios.com.ar/disaster-recovery/
- In Spanish: [Recuperación ante desastres](https://tidbit.legios.com.ar/es/disaster-recovery/)

**Disaster recovery** (DR) is how an organization gets its systems running again after something big goes wrong: a whole data center or cloud region goes down, a ransomware attack encrypts the servers, a bad deploy corrupts the database, or a flood reaches the building. Backups are part of it, but DR is the whole plan: what gets restored first, where it runs, who decides, and how long it all takes.

Two numbers shape every plan. The **RPO** (recovery point objective) is how much data you can afford to lose, measured in time: an RPO of one hour means losing at most the last hour of changes. The **RTO** (recovery time objective) is how long you can afford to be down. A blog might accept a day for both; a payment system may need seconds. Tighter numbers cost more, because they require more copies, more automation and spare capacity sitting ready.

On the cloud, common strategies go from cheap and slow to expensive and fast: **backup and restore** in another region, a **pilot light** with only the core pieces running, a **warm standby** with a smaller copy of everything, and **active-active**, where two regions serve traffic at the same time. Whatever the choice, the plan only works if it is practiced; teams run regular drills where they actually fail over and time how long it takes.

## An analogy

A fire drill for your systems. Having extinguishers is the backup; knowing the exits, who calls whom and where everyone meets is the disaster recovery plan, and you only know it works if you have practiced it.

## Keep in mind

- Covers restoring systems and data after a big failure, not just keeping copies.
- RPO: how much data you can lose. RTO: how long you can be down.
- Strategies range from backup and restore to active-active across regions.
- Untested plans fail; run drills regularly.

## Go deeper

- [What is disaster recovery? (AWS)](https://aws.amazon.com/what-is/disaster-recovery/)
- [Disaster recovery of workloads on AWS (whitepaper)](https://docs.aws.amazon.com/whitepapers/latest/disaster-recovery-workloads-on-aws/disaster-recovery-workloads-on-aws.html)
- [Disaster recovery on Wikipedia](https://en.wikipedia.org/wiki/Disaster_recovery)

## Related terms

- [Data center](https://tidbit.legios.com.ar/data-center/): A building full of servers where the internet, the cloud and AI actually run.
- [Cloud computing](https://tidbit.legios.com.ar/cloud-computing/): Renting computers over the internet instead of buying your own.
- [Regions and Availability Zones](https://tidbit.legios.com.ar/regions-and-availability-zones/): Where AWS physically lives: cities worldwide, each split into separate data centers.
- [Malware and ransomware](https://tidbit.legios.com.ar/malware-and-ransomware/): Software built to harm you; ransomware locks your files and charges to unlock them.
- [Server](https://tidbit.legios.com.ar/server/): A computer whose job is to answer requests from other computers, all day, every day.
- [Database](https://tidbit.legios.com.ar/database/): An organized store of data that programs can search and update safely.
- [Backup](https://tidbit.legios.com.ar/backup/): A separate copy of your data, kept so you can get it back when the original is lost.