I would like to mention this Veeam Article that was useful in the past to configure Direct SAN Access feature to enhance Backup Veeam Speed and workload.
Direct SAN Access
The Direct SAN access transport mode is recommended for VMs whose disks are located on shared VMFS SAN LUNs that are connected to ESX(i) hosts over FC, FCoE, iSCSI, and on shared SAS storage.
In the Direct SAN access transport mode, Veeam Backup & Replication leverages VMware VADP to transport VM data directly from and to FC and iSCSI storage over the SAN. VM data travels over the SAN, bypassing ESX(i) hosts and the LAN. The Direct SAN access transport method provides the fastest data transfer speed and produces no load on the production network.
The Direct SAN access transport mode can be used for all operations where the backup proxy is engaged:
Backup
Replication
VM copy
Quick migration
Full VM restore
VM disk restore
Replica failback
