Incremental Snapshots in Azure AKS

[egondalia]

Using Azure AKS Cluster with the latest "Velero" and "Velero-Plugin-for-Azure" <<

We install Velero with Velero Azure Plugin and enable 'incremental' backup option/switch but unable to validate a simple test to confirm incremental backups are functioning on Azure Disks, we have set option on the VolumeSnapShotLocation and enabled it ok:
(note: my UUID and ResGrp has been changed removed)

kubectl describe VolumeSnapShotLocation -n velero

Name:         default
Namespace:    velero
Labels:       component=velero
Annotations:  <none>
API Version:  velero.io/v1
Kind:         VolumeSnapshotLocation
Metadata:
  Creation Timestamp:  2024-09-06T16:14:45Z
  Generation:          1
  Resource Version:    349621
  UID:                 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Spec:
  Config:
    API Timeout:      5m
    Incremental:      true
    Resource Group:   XXXXXXXXXXXXXXXXXXXXXXX
  Provider:           azure
  Events:               <none>

   
#kubectl describe VolumeSnapShotLocation -n velero | grep Incremental
    Incremental:      true

We perform scheduled daily backups on pod/app (and fill up data daily on the pv/disk), but after an initial full backup, when we run additional backups (that should now perform differential backups) when we look at backup files location used by the Velero storage the files don't seem to change in size for additional backups after the initial first backup takes place, files don't appear to be smaller in size.

Q) Is there way we can validate that incremental snapshot are working and/or a way to check these size changes when running additional incremental backups ?

We found reference/discussions post (see link below) and our understanding once "Incremental" is set in our case we use the azure plugin, then Azure is able to take incremental backups, but we are unable can't specifically validate that incremental snapshots are working.

The discussions/posts below seems to state the incremental snapshot is done on the azure abstraction layer and there is no easy way to validate it. See link [https://github.com//issues/7276]

..... as long as it shows incremental you can be rest assured it is incremental in nature. Size only indicates the size of the disk when you restore it. ( "diskSizeBytes": 1073741824,). It is not the snapshot size, but the disk size.
To get fine grain details on how to validate the actual consumption, that is the only part you can check with azure support.

I would appreciate help/confirmation that this is the case no being able to validate incremental snapshots on Azure, or ideally is there a method we can use to validate/test this.