Howto migrate AKS CSI StorageClass from LRS to ZRS

Question

Is it possible to migrate a StorageClass from LRS CSI StorageClass to ZRS?

Likewise migrate PVs/PVCs to ZRS?

If so, what would be the process?

Answer 1

Hello Kirrane, Desmond (Dessie)

If it is an AKS-managed StorageClass, it is not recommended to change it.

To identify an AKS-managed StorageClass, you can generate its yaml (kubectl get sc <sc-name> -o yaml) and look for label "addonmanager.kubernetes.io/mode"

To modify your existing StorageClass to use ZRS, you can use the below:

parameters:
  skuName: Standard_ZRS

You can also create a new StorageClass with ZRS.

You can refer to the below example and adapt it as needed:

allowVolumeExpansion: true
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: azurefile-csi-zrs
mountOptions:
- mfsymlinks
- actimeo=30
- nosharesock
parameters:
  skuName: Standard_ZRS
provisioner: file.csi.azure.com
reclaimPolicy: Delete
volumeBindingMode: Immediate
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  creationTimestamp: "2023-03-07T08:28:21Z"
  labels:
    addonmanager.kubernetes.io/mode: EnsureExists
    
  name: azurefile-csi
  resourceVersion: "361"
  uid: d37b01e9-c284-405a-8539-1fab044571a6
mountOptions:
- mfsymlinks
- actimeo=30
- nosharesock
parameters:
  skuName: Standard_LRS
provisioner: file.csi.azure.com
reclaimPolicy: Delete
volumeBindingMode: Immediate
allowVolumeExpansion: true
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: azurefile-csi-zrs
mountOptions:
- mfsymlinks
- actimeo=30
- nosharesock
parameters:
  skuName: Standard_ZRS
provisioner: file.csi.azure.com
reclaimPolicy: Delete
volumeBindingMode: Immediate

Note there is also the Premium_ZRS option

To migrate, you may want to use the snapshot feature. Reference links for Azure Disk and Azure File:

https://learn.microsoft.com/en-us/azure/aks/azure-files-csi#create-a-custom-storage-class
https://learn.microsoft.com/en-us/azure/aks/azure-disk-csi#volume-snapshots

Please make sure to test on some test resources as I personally didn't implement this scenario, but it is possible to be achievable using volume snapshots.

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I hope this is helpful. If any clarification needed, let me know and I will do my best to answer.

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Thank you!