Is the vmkernel network limited to 40% for backup traffic?

[Luca82]

Hi everyone, I am setting up a backup solution which uses the vmkernel management network for data tranfert (NBD).
I read in this link
https://www.veeambp.com/proxy_servers_i ... _mode#pros
ad focus on the following point:
"Typically, network mode uses only up to 40% of the available bandwidth of the external VMKernel interface due to throttling mechanisms implemented on the management interfaces."

So...what means "tipically" and where can I found a VMware or Veeam KB/documentation about that? I already check on vmware community but it seems that no one knew about that information.
Can you please help me to understand if is it true and if there is an official documentation/kb or prove about that?

Thank you

[foggy]

I'm not sure there's any official documentation on that, it's mostly a common knowledge that is based on real-world experience.

[Gostev]

Yep, basically this number was obtained empirically (based on real-world observations).

[MAA]

foggy
Gostev

Can you, as representatives of the Veeam company, send an official request to VMware about this?

[Gostev]

The first time we did this was well over 10 years ago.

[MAA]

and?

[Gostev]

And they still did not fix it, as you may have noticed which to me indicates an architecture limitation that cannot be addressed without a complete re-write.

[MAA]

I would like to know what they answered to your request?

[Gostev]

Sorry but we're bound by NDA on our communications with their development and product management.

Try asking on their forums about this issue, may be my counterpart there would be willing to share their plans.
This is a known limitation and trust me, they are well aware of it... they obviously do their own tests too!

[MAA]

I have already asked but did not receive an answer
https://communities.vmware.com/t5/ESXi- ... -p/2879040
my limit is 20% for vmkernel network

[Gostev]

I just wanted to note that the operation you are performing there does not use VDDK in network transport mode (aka NBD) which is what is being discussed in this topic. Rather, it uses an internal vSphere API called NFC which has its own quirks.