Restore cluster with a Rancher snapshot
This doc describes what users need to do after restoring the cluster with a Rancher snapshot.
Disable Revision Counteris false. (It’s false by default.) Otherwise, users need to manually check if the data among volume replicas are consistent, or directly restore volumes from backup.
Restart all Kubernetes components for all nodes. See the above link for more details.
Kill all longhorn manager pods then Kubernetes will automatically restart them. Wait for conflicts in longhorn manager pods to disappear.
All volumes may be reattached. If a Longhorn volume is used by a single pod, users need to shut down then recreate it. For Deployments or Statefulsets, Longhorn will automatically kill then restart the related pods.
If the following happens after the snapshot and before the cluster restore:
A volume is unchanged: Users don’t need to do anything.
The data is updated: Users don’t need to do anything typically. Longhorn will automatically fail the replicas that don’t contain the latest data.
A new volume is created: This volume will disappear after the restore. Users need to recreate a new volume, launch a single replica volume based on the replica of the disappeared volume, then transfer the data to the new volume.
A volume is deleted: Since the data is cleaned up when the volume is removed, the restored volume contains no data. Users may need to re-delete it.
For DR volumes: Users don’t need to do anything. Longhorn will redo a full restore.
Some operations are applied for a volume:
Notice: If users don’t know how to recover a problematic volume, the simplest way is always restoring a new volume from backup.
If the Longhorn system is upgraded after the snapshot, the new settings and the modifications on the node config will disappear. Users need to re-do the upgrade, then re-modify the settings and node configurations.
If a node is deleted from Longhorn system after the snapshot, the node won’t be back, but the pods on the removed node will be restored. Users need to manually clean up them since these pod may get stuck in state
If a node to added to Longhorn system after the snapshot, Longhorn should automatically relaunch all necessary workloads on the node after the cluster restore. But users should be aware that all new replicas or engines on this node will be gone after the restore.
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