slow performance hyper-V file server on dedup enabled VHDX

[CALCM1985]

We've recently installed Veeam Backup & Replication.
All VM's are backup-ed at normal speed. However, our file server (about 1.1TB) is backing up at slow rate of +-6MB/s.
This is taking so long, that the backup task fails every time.
To exclude interference, I've created a separate backup task which runs alone.

Veeam server is a Hyper-V VM Windows server 2012R2 (8GB RAM, 4 cores)
Backup target is Q-Nap
File server contains multiple VHDX, only the ones with server 2012 data-dedup appear to experience this problem.
Bottleneck according to Veeam is 'target'. Normal file copy's to the target are high speed.

[Vitaliy S.]

Hi Nicolas,

Do you see normal job performance when you exclude these disks from the backup job? If yes, then what are the rates? Do you store these disks on the same storage?

Thanks!

[CALCM1985]

When I exclude these disk, get a processing rate of 16MB/s (which is still rather slow) but this time the bottleneck moved to the network. (I'll need to look into that)
The original VHDX run on a MSA2040 SAN and are backup-ed to a Q-Nap NAS

[Vitaliy S.]

What are full bottleneck stats (including all components) for this job?

[CALCM1985]

where can i find these stats? (Job has never been fully completed)

[foggy]

They are logged at the end of the job session. I recommend contacting support with this though.