I have Elasticsearch Data pods that are currently running on an AKS and are connected to Persistent Volumes that is using a Premium SSD Managed Disk Storage Class and I want to downgrade it to Standard SSD Managed Disk without losing the data I have on the currently used Persistent Volume. I've created a new Storage Class that is defined with Standard SSD Managed Disk, but if I create a new PV from that it obviously doesn't keep the old data and I need to copy it somehow, so I was wondering what would be best practice switching PV's Storage Class.

CodePudding user response：

Unfortunately, once a PVC is created and a PV is provisioned for it, the only thing you can change without creating a new one is the volume's size

The only straightforward way I could think of without leveraging CSI snapshots/clones, which you might not have access to (depends on how you created PVCs/PVs AFAIK), would be to create a new PVC and mount both volumes on a Deployment whose Pod has root access and the rsync command.

Running rsync -a /old/volume/mount/path /new/volume/mount/path on such a Pod should get you what you want.

CodePudding user response：

It is not possible in Kubernetes to change the storage class of a PVC - because of the described reason. Unfortunately you have to create a new PVC with the desired storage class.

CodePudding user response：

One way to go about this would be to create a snapshot and then new volume from the that snapshot : https://kubernetes.io/docs/concepts/storage/volume-snapshots/

Another is to leverage CSI cloning : https://kubernetes.io/docs/concepts/storage/volume-pvc-datasource/

Both effectively facilitate creation of a fresh PV with a copy of existing data