A disaster can be any event that puts your applications at risk, from network outages to equipment failures to natural disasters. A well-architected disaster recovery plan enables you to recover quickly from disasters and continue to provide services to your users.

Oracle Cloud Infrastructure (OCI) provides highly available, secure, and scalable infrastructure and services that enable you to recover your cloud workloads quickly, reliably, and securely. A natural disaster can cause an entire OCI region to be out of service. This scenario is one of the most severe cases in your disaster recovery design. To protect against this scenario, deploy your workloads across multiple OCI regions. Depending on your disaster recovery goals, whether recovery time or point objectives (RTO and RPO), you can back up or replicate your data to another region.

Cross-region replication

One of the ways to set up disaster recovery for Compute instances is cross-region replication of block volumes, boot volumes, and volume groups to other regions. The Block Volume service enables you to perform ongoing automatic asynchronous replication of block volumes, boot volumes, and volume groups to other regions. This feature supports the disaster recovery scenario without requiring volume backups and volume group backups.

The cross-region replication feature is complementary to the backup feature, not a replacement. Backups give you a point-in-time snapshot of volumes that enables you to return to a previous version of a volume or volume group. Replicas give you the current version of the data.

When you enable replication for a volume or volume group, the process includes an initial sync of the data from the source to the replica. Depending on volume size and the amount of data written to volumes, this sync can take hours after the initial synchronization process is complete. The replication process is continuous, with the typical recovery point object (RPO) target rate being less than thirty minutes. However, the RPO can vary. For more information, see Limitations and Considerations.

Set up multiregion disaster recovery for Compute instances

We have an example of setting up multiregion disaster recovery for the virtual machine (VM) “prod-1” using cross-region replication of the boot volume of the VM. The primary region is Ashburn, and the disaster recovery region for the VM is London. For more information, see Region Mappings.

  1. We start at prod-1’s boot volume in the Ashburn region. Currently, cross-region replication is turned off. Click the Edit button.

    A screenshot of the Boot Volume Details page with the edit button outlined in black.

  2. Turn on cross-region replication.

    1. Select a region as your disaster recovery region (for example, London).

    2. Choose an availability domain.

    3. Name the replica.

    4. Select Confirm and click Save Changes.

      A screenshot of the Edit Volume page showing the Cross Region Replication selection on and the Save Changes button outlined in black.

     

  3. Cross-region replication on prod-1’s boot volume is turned on.

    A screenshot of the Boot Volume Information page with the Cross Region Replication section outlined in red.

  4. Now we’re in our disaster recovery region London. We can see prod-1_replica is successfully created. The initial sync of the data from the prod-1 boot volume to the replica is done and the state is available. Because the replication process is continuous, it asynchronously replicates the prod-1 boot volume (Ashburn) to prod-1_replica (London Region) with the typical RPO target rate being less than thirty minutes, but the RPO can vary. For more information, see Limitations and Considerations.

    A screenshot of the created boot volume replica.

  5. In a disaster situation, if the Ashburn region goes down, you can create the boot volume in the London region using prod-1_replica by clicking Activate.

    A screenshot of the boot volume replica page with the Created menu expanded and the option to Activate highlighted.

  6. Give the boot volume replica details and click Activate replica.

    A screenshot of the Activate Replica window with the details selected and the Activate Replica button outlined in black.

  7. As soon as you click, a boot volume is provisioned in the London region.
    A screenshot of the Boot Volume Details page of the replica.

  8. Using that boot volume, you can create the disaster recovery VM in the London region. Click Create Instance and give the VM details.

    A screenshot of the Boot Volume Details page with the Create Instance button outlined in black.

  9. The disaster recovery VM is now created in the London region.

    A screenshot of the Work Requests page on the Instance Information tab.

Conclusion

In this post, we learned how we can set up multiregion disaster recovery for Compute instances using the boot volume’s cross-region replication feature. For more details, see the following references: