OpenShift Disaster Recovery Limitations
The OpenShift Container Platform provides the option to recover from several disaster situations by restoring your cluster to a previous state. This can be a recovery option if an administrator deletes something critical or if you have lost the majority of your control plane hosts, leading to etcd quorum loss and the cluster going offline.
This document focuses on the limitations of restoring a previous cluster state and when it’s not the solution.
Restoring to a previous cluster state allows you to recover from a lost control plane. However there are some important limitations that can prevent us from restoring a cluster.
Disaster recovery requires you to have at least one healthy control plane host that’s reachable by SSH
When you restore your cluster, you must use an etcd backup that was taken from the same z-stream release
Restoring Cluster after complete Control Plane loss
Restoring cluster state without at least one healthy control plane host isn’t supported. Trying to restore a previous cluster state to a newly created cluster will lead to a mix of certificates and IDs and the cluster won’t be able to start.
In case of a complete loss of all control plane hosts, we recommend creating a new cluster and re-deploying the workloads of the lost cluster. This can be done by restoring objects from backup.
You might be able to restore a previous cluster state to a newly created cluster by manually updating certificates and fixing inconsitent state. This is however not supported and can lead to unforeseen issues. We don’t recommend doing this.
Rollback after cluster upgrade
Downgrading a cluster after a faulty upgrade isn’t supported . It’s also not possible to restore a cluster to a previous cluster state with a different OpenShift version . This means there is no official way to rollback a faulty OpenShift upgrade.
An unrecoverable cluster upgrade failure is effectively a complete loss of the old cluster. We recommend creating a new cluster and re-deploying the workloads of the lost cluster by restoring objects from backup.
This limitation not only applies to major or minor version upgrades but also to patch upgrades. This means when you restore your cluster, you must use an etcd backup that was taken from the same z-stream release. For example, an OpenShift Container Platform 4.7.2 cluster must use an etcd backup that was taken from 4.7.2