DS-Client Help : Working with backups : VMware vCenter Server backups (Windows or Linux) : Using VMware transport libraries
 
Using VMware transport libraries
VMware transport libraries are included with the DS-Client to allow VMware to take advantage of the different transport modes that are supported when accessing the VMware VMFS datastore using the Fibre Channel (FC), Fibre Channel over Ethernet (FCoE), or iSCSI protocols.
By default, the DS-Client uses VADP and VDDK APIs to interact with the VMWare ESXi environment for backup and restore. The DS-Client automatically uses the most efficient transport mode available and deduplicates, compresses, and encrypts the virtual machine before sending the data to the DS-System. For more information, see the VMware documentation.
The following VMware virtual disk transport methods are used:
• NBD (Network Block Device) and NBDSSL (encrypted) transport mode — Allows you to transfer data over the LAN when the DS-Client is running on a physical or virtual machine and does not have direct access to the VMware VMFS datastore. The DS-Client reads from the .vmdk virtual disks where the data is stored and transfers the data from the ESXi host to the DS-Client.
• SAN (Storage Area Network) transport mode — Allows you to transfer data over the SAN when the DS-Client is running on a physical machine and has direct access to the VMware VMFS datastore. The DS-Client reads the data directly from the SAN storage where the .vmdk virtual disks are stored. No data is transferred over the LAN from the ESXi host to the DS-Client. When using this method to perform a restore, the DS-Client automatically disables the CBT parameters in the virtual machine advanced settings.
• HotAdd transport mode — Allows you to transfer data over the SAN when the DS-Client is running on a virtual machine and has direct access to the VMware VMFS datastore where the source virtual machines are located. The DS-Client reads the data directly from the SAN storage where the .vmdk virtual disks are stored. No data is transferred over the LAN from the VMware ESXi host to the DS-Client. The HotAdd transport mode is supported only when the virtual machines being backed up are using SCSI virtual disks.