Backup from Storage Snapshots and Direct NFS are the preferred processing modes for NFS datastores, as they offer the best performance and reliability for backup and restore operations12.

Backup from Storage Snapshots is a feature of Veeam Backup & Replication that leverages the native snapshot capabilities of the storage system to create a consistent point-in-time copy of the VM data. Veeam Backup & Replication then reads data directly from the storage snapshot, bypassing the ESXi host and reducing the impact on the production environment3. Backup from Storage Snapshots is supported for NFS datastores on NetApp, Nimble, Dell EMC, HPE, and Pure Storage systems4.

Direct NFS is a proprietary transport mode of Veeam Backup & Replication that uses a native NFS client deployed on the backup proxy to read and write data directly from and to the NFS datastore. Veeam Backup & Replication also bypasses the ESXi host and reduces the load on the production environment. Direct NFS is supported for NFS datastores on any storage system that supports NFS version 3 or 4.1.

The other options are not preferred because:

B) Network (NBD) mode is a transport mode that uses the VMware VDDK to communicate with the ESXi host over the network. This mode produces additional load on the ESXi host and the network, and may result in slower backup and restore performance.

C) Virtual Appliance (HotAdd) mode is a transport mode that uses the VMware VDDK to attach the disks of the processed VM to the backup proxy VM. This mode also produces additional load on the ESXi host and the network, and may cause issues with disk alignment or SCSI controller limitations.

D) Network mode with Encryption (NBDSSL) mode is a transport mode that uses the VMware VDDK to communicate with the ESXi host over the network with SSL encryption. This mode provides an extra layer of security, but also adds more overhead and reduces the backup and restore performance.

You can find more information about the processing modes and how to choose the best one for your environment in the following resources:

Transport Modes

Selecting a Transport Mode

Backup from Storage Snapshots

Storage Systems Supported for Backup from Storage Snapshots

[Direct NFS Access]

[Network Mode]

[Virtual Appliance Mode]

[Network Mode with Encryption]