What backup speed should I expect?

[NashBrydges]

Here is the scenario...

Host A: Hyper-V VM Host
Dell R510 with 2 x E5645 CPUs, 96GB RAM, 12 x 6TB SATA 6G drives in RAID10
Intel X520-DA2 10G NIC - 1 x 10G connected to switch - 1 x 10G direct connect to Backup Repository Host - All NICs have jumbo frames enabled

Host B: Backup Repository
Dell R510 with 2 x E5645 CPUs, 96GB RAM, 12 x 6TB SATA 6G drives in RAID10
Intel X520-DA2 10G NIC - 1 x 10G connected to switch - 1 x 10G direct connect to Hyper-V Host - All NICs have jumbo frames enabled
Veeam B&R 9.5 installed on this server as a VM with 4 cores and 16GB RAM

Essentially mirrored servers with one backing up to the other. The Hyper-V host (Host A) has a single VM file server with 26TB video content. No other VMs running on either R510 servers.

The backup speeds hover around 270MB/s and the bottleneck is shown as "Source"

The source server (Host A) shows 25% CPU and 18% RAM utilization.

I'd love to saturate the 10G direct connection between the 2 servers during backup to shorten my backup window. Any ideas where to look first?

[foggy]

The speed is pretty good, but there will always be the bottleneck at some stage, since some part of the chain is always weaker than the others. Having several simultaneous jobs could probably allow to saturate the link, but you have just a single VM, so this is not the case.