VM Transport Modes

VMware Transport Modes

The VMware^® VADP framework provides several transport modes to protect virtual machines:

• SAN transport mode
• NAS transport mode
• HotAdd mode
• NBD and NBD SSL mode

Each of these modes has their advantages and disadvantages. Variables such as physical architecture, source data location, ESX resources, network resources and VSA proximity to MediaAgents and storage have an effect on determining which mode is best to use. It is also recommended to consult with Commvault for design guidance when deploying Commvault^® software in a VMware environment.

SAN Transport Mode

SAN Transport Mode is used on a VSA access node with direct Fibre channel or iSCSI access to snapshot VMs in the source storage location. This mode provides the advantage of avoiding network movement of VM data and eliminates load on production ESX servers.

Virtual machines are backed up through the VSA and to the MediaAgent. If the VSA is installed on an access node configured as a MediaAgent with direct access to storage, LAN-Free backups can be performed. For best performance, Commvault recommends that the VSA have a dedicated HBA to access the VMDK files. If an iSCSI SAN is used, we recommend a dedicated Network Interface Card on the VSA for access to the SAN.
 
VSA backup process using SAN transport mode

NAS Transport Mode

NAS Transport Mode is used on a VSA access node with direct network access to the datastore NFS volume exports in the source NAS filer. This mode provides the advantage of avoiding data movement of VM data through the production ESX servers.

Virtual machines are backed up through the VSA and to the MediaAgent. In such scenario, the VSA access node is typically installed directly on the physical MediaAgent. For best performance, Commvault recommends that the VSA have a dedicated Network Interface Card for access to the NAS.

VSA backup process using NAS transport mode

HotAdd Mode

HotAdd mode uses a virtual VSA in the VMware environment. This requires all data to be processed and moved through the VSA access node on the ESX server. HotAdd mode has the advantage of not requiring a physical VSA access node and does not require direct SAN access to storage. It works by 'hot adding' virtual disks to the VSA access node and backing up the disks and configuration files to protected storage.

A common method of using HotAdd mode is to use Commvault deduplication with client-side deduplication, DASH Full and incremental forever protection strategy. Using Change Block Tracking (CBT), only changed blocks within the virtual disk have signatures generated and only unique block data are protected.

This mode is also useful when there is no physical connectivity between the physical VSA access node and the Datastore storage preventing the use of SAN transport mode. Some examples of such scenarios are when using NFS Datastores or using ESX hosts local disk storage to host Datastores.

VSA backup process using HotAdd transport mode

NBD Mode

NBD mode uses a VSA access node installed on a physical host. The VSA connects to VMware and snapshots will be moved from the ESX server over the network to the VSA access node. This method requires adequate network resources. NBD mode is the simplest method to protect virtual machines.

VSA backup process using NBD transport mode

Hyper-V Transport Modes

Commvault^® software uses VSA access nodes to facilitate the movement of virtual machine data during Hyper-V backup operations. The VSA access nodes are identified in the instance properties. For Microsoft Hyper-V, the VSA is installed on each hypervisor host. VMs can be protected from each host or a VSA access node can be designated to protect VMs. The access node must have access to all clustered shared volumes where VMs reside.

Hyper-V Transport Mode