Data Manager support HotAdd and NBD transport modes, the transport mode that is selected when adding the VM Direct Engine appliance (Hot-Add, Network Block Device, or the default setting Hot Add, Failback to Network Block Device). In NBD mode, the ESX/ESXi host reads data from storage and sends it across a network to the target storage.
As its name implies, this transport mode is not LAN‐free, unlike SAN transport.
HotAdd is a VMware feature where devices can be added “hot” while a virtual machine is running. Besides SCSI disk, virtual machines can add additional CPUs and memory capacity. If backup software runs in a virtual appliance, it can take a snapshot and create a linked clone of the target virtual machine and then attach and read the linked clone’s virtual disks for backup. This involves a SCSI HotAdd on the ESXi host where the target virtual machine and backup proxy are running. Virtual disks of the linked clone are Hot Added to the backup proxy. The target virtual machine continues to run during backup.
