We've documented the API generally, but it appears we have a gap in that we do not describe the process of PV discovery and what customers should expect to find the controller writing back to the MigPlan, and how they should fill out the selection section of the CR.

In particular, we have a customer interested in migrating between storageclasses (cephfs -> cephrdb) where they have to also change the destination access mode. This should be documented in our upstream documentation, and we'll also want the same thing downstream.

We need to document for customers the following process:

  - capacity: 10Gi
    name: pvc-095a6559-b27f-11eb-b27f-021bddcaf6e4
    proposedCapacity: 10Gi
    pvc:
      accessModes:
      - ReadWriteMany
      hasReference: true
      name: mysql
      namespace: mysql-persistent
    selection:
      action: copy
      copyMethod: filesystem
      storageClass: cephrbd
    storageClass: cephfs

Above is probably similar to what your customer's migplan persistentVolumes list looks like.

Source cluster has RWX and cephfs, and UI-chosen selection is "change this to cephrbd"

So what you'd need to do is to oc edit the migplan and add an accessMode selection.

add accessMode: ReadWriteMany to the selection section.

So it would look like this:

  - capacity: 10Gi
    name: pvc-095a6559-b27f-11eb-b27f-021bddcaf6e4
    proposedCapacity: 10Gi
    pvc:
      accessModes:
      - ReadWriteMany
      hasReference: true
      name: mysql
      namespace: mysql-persistent
    selection:
      action: copy
      copyMethod: filesystem
      storageClass: cephrbd
      accessMode: ReadWriteMany
    storageClass: cephfs

thanks to sseago for the above process