About Azure snapshots
NetBackup 9.0 introduces incremental snapshots in Azure. NetBackup creates the incremental snapshots for new changes to the disks, since the previous snapshot. The snapshots are independent of each other, for example, deletion of one snapshot, does not affect the subsequent snapshot that NetBackup creates. The incremental snapshots significantly reduce the cost of backup by reducing the required disk space, and using the Azure Standard HDD as storage, instead of Premium HDD.
You can configure the backup and restore policies in NetBackup to create and schedule the incremental snapshots for your data. NetBackup takes incremental snapshots till Azure's incremental snapshot limit is reached, after that, full snapshots are taken.