This article describes the proper precautions to take when expanding storage size on a production machine.
It is essential to have is enough space available on the Datto device to accommodate the increased storage amount on the protected machine. Without enough space, the disk array can fill, causing backups to fail. Since all sectors will be different on the block level, differential merges will fail as well.
Often, space can be regained on the Datto device by deleting redundant local backup points in the web UI. If more space on the Datto device is necessary to accommodate the protected machine's larger disk size, speak with your sales representative about increasing capacity.
Expanding storage by creating a thick-provisioned volume which is seen as a different disk