> Documentation > Backup and Restore Agents > Virtualization > Virtual Server Agent > VMware > Transport Modes

NAS Transport for VMware

The NAS (network attached storage) transport mode enables the virtual server agent (VSA) proxy computer to read data directly from the network file server (NFS), without going through an ESX host or transferring data over the local area network (LAN).

When the automatic transport mode selection feature is enabled, and the NAS storage is connected to the ESX host, the NAS transport mode is automatically selected for the supported backup and restore operations. With this, the VSA must have access to the datastore NFS volume exports that provide storage for the virtual machine disks. Data is read directly from the storage where the virtual machines reside, without going through the ESX host or transferring data over the LAN between the ESX host and the VSA proxy. The ESX host is contacted only to coordinate access to the NFS datastore.

You can use the NAS transport mode for the following operations:

  • Streaming backups

  • Backup copies

  • Full VM restores

Benefits

The benefits of using the NAS transport mode for backup and restore operations are as follows:

  • The NAS transport mode does not require an ESX proxy host computer.

  • The NAS transport mode can reduce the need for mount operations.

  • The NAS transport mode increases the performance of streaming backup operations and backup copy operations because the data is directly transferred from the NFS to the proxy computer (which is the MediaAgent).

When to Use the NAS Transport Mode

Use the NAS transport mode in the following scenarios:

  • The Virtual machines that are backed up are on NFS datastores.

  • Each proxy that performs backup operations is a Windows physical server, a Linux physical server, or a Linux virtual machine proxy with access to the datastore NFS share.

  • Each MediaAgent has local access to directly connected storage using a shared mount path.

Do not use the NAS transport mode in the following scenarios:

  • Local datastores are available only within the ESX server environment.

  • The storage where the virtual machines reside is accessed using the Fibre Channel Protocol (FCP) or the iSCSI SAN protocol.

Considerations

Consider the following when using the NAS transport mode:

  • For streaming operations, Windows VSA VM proxies use the HotAdd mode instead of the NAS transport mode because HotAdd performs better.

  • For other NFS storage vendors, the hardware snapshot datastore is mounted to a proxy ESX server, and therefore, uses the NAS transport mode during backup operations.

  • In a physical proxy configuration, the VSA and the MediaAgent are installed on a physical server that can connect to the NAS network. Backups in a purely physical implementation include only NAS devices.

  • For backup copy operations and restores from IntelliSnap backups, the following are true:

    • For NetApp NFSv3, you can explicitly select the NAS transport mode to perform IntelliSnap backups or backup copy operations. Backup copy operations do not mount the hardware snapshot datastore to a proxy ESXi host (ESX proxyless backups).

      For NetApp NFSv4 and other NFS storage vendors, IntelliSnap backup copy operations mount the hardware snapshot datastore to a proxy ESX server and use the NBD transport mode.

      For subclients that contain virtual machines from both VMFS and NFS datastores:

      • Backup copy operations for VMs on NFS datastores mount the hardware snapshot datastore to a proxy ESX server and use the NBD transport mode.

      • Backup copy operations for VMs on VMFS datastores use the SAN transport mode if array and volume mappings are exposed to a VSA proxy on a physical machine. If the VSA proxy is a virtual machine or if array and volume mappings are not exposed to the VSA proxy, backup copy operations mount the hardware snapshot datastore to a proxy ESX server and use the NBD transport mode.

    • Live Browse for IntelliSnap uses the NBD (network block device) transport mode.

System Requirements

  • You can use the NAS transport mode only with proxy computers that are hosted on Windows physical computers, Linux physical computers, and Linux virtual machines. If the proxy is hosted on a Windows virtual machine, then use a HotAdd or NBD mode configuration on the deployed proxy.

  • VSA proxies must have access to NFS exports from the NFS server.

  • The proxy machine must have access to the NFS ports for the destination NFS server behind any firewall configuration.

  • When running as root, libnfs tries to allocate a system port for its connection to the NFS server. When running as non-root, libnfs uses a normal ephemeral port. By default, many NFS servers do not allow non-system ports to connect. For these NFS servers, you must use the "insecure" export option in /etc/exports to allow libnfs clients to connect.

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