Disaster Recovery Strategies for Business-Critical K8s Workloads

Many IT managers in medium-sized businesses feel secure because they “do backups.” However, in a serious incident—such as a massive cloud provider outage, a ransomware attack, or a human error in the root config—they realize: A backup is not a recovery plan.

In the Cloud-Native world, Disaster Recovery (DR) means more than just restoring data. It means quickly restoring the entire application topology.

Backup vs. Disaster Recovery: A Crucial Difference

A backup is a copy of data. Disaster Recovery is the process framework to restore business operations within a defined time. Two key metrics play a major role:

• RPO (Recovery Point Objective): How much data loss can we tolerate? (e.g., “The last 15 minutes of data”).
• RTO (Recovery Time Objective): How quickly must we be back online? (e.g., “Within 2 hours”).

Strategies for Kubernetes: From “Backup” to “Multi-Site”

Depending on the criticality of your applications, three different architectural patterns are available:

1. Backup & Restore (The “Cold” Approach)

The simplest way. With tools like Velero, we back up the cluster state (YAML manifests, Persistent Volumes, Secrets) to an S3 storage—ideally with another provider or on-premises.

• Advantage: Cost-effective.
• Disadvantage: High RTO. In a serious case, a new cluster must be provisioned and all data restored. This can take hours.

2. Pilot Light (The “Warm” Approach)

A minimal standby cluster runs in a second region or another data center. Only the absolutely critical core components (e.g., database replication) are active.

• Advantage: Significantly faster RTO.
• Challenge: Requires clean automation via GitOps (ArgoCD/Flux) to ensure that the application configuration remains identical in both clusters.

3. Multi-Site Active-Active (The “Hot” Approach)

Workloads run simultaneously in two clusters. A global load balancer distributes the traffic.

• Advantage: Near-zero RTO/RPO. If one site fails, the other takes over seamlessly.
• Technique: Service meshes like Istio or Linkerd are used here to enable cross-cluster communication.

The Role of Velero and GitOps

For medium-sized businesses, a combination of Velero and GitOps is often the “sweet spot.”

1. GitOps (Code Level): All K8s manifests are stored in Git. If the cluster dies, we rebuild it via script, and ArgoCD automatically redeploys all apps.
2. Velero (Data Level): Since database contents are not stored in Git, Velero backs up the Persistent Volumes (PVs) and ensures that data states are consistently restored.

Conclusion: Test the Real Case (Chaos Engineering)

A DR plan that hasn’t been tested doesn’t work. We recommend regular “Game Days”: Intentionally shut down a test cluster and measure how long it takes your team to restore it with the available tools. Only then will you know if your cloud strategy is truly crisis-proof.

Technical FAQ: Disaster Recovery

Should backups be with the same provider? Absolutely not. If AWS has a massive issue in the Frankfurt region, there’s a good chance your S3 bucket there will be affected too. Use “cross-provider” backups (e.g., backups from AWS to an S3 with Wasabi, IONOS, or on-prem).

How do I handle databases? Kubernetes snapshots (via CSI) are good, but often not “application consistent” for databases. Additionally, use native database tools (e.g., pg_dump or Barman for Postgres), which are triggered by Velero with a hook before the backup.

Is a Git repository sufficient as a recovery source? For application logic, yes. But be cautious: Secrets (passwords, certificates) are often encrypted in the cluster or managed externally (e.g., HashiCorp Vault). Ensure these vaults are also part of the recovery plan.