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Luca82
Enthusiast
Enthusiast

Is the vmkernel network limited to 40% for external requests (for example backup)?

Hi everyone, I am setting up a backup solution wich uses the management network for data tranfert. As I know the management network is throttled to 40% of bandwdth but I don't find any vmware documentation about that.....can you please help me to understand if is it true and if there is an official documentation/kb about this topic?

Thank you

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MartinGustafsso
VMware Employee
VMware Employee

Hi,

No, the management vmkernel (usually vmk0) is not limited to 40% of available bandwidth.

You can use iPerf to test your throughput.

Note that you can setup reservations and limits for network traffic using Network I/O control.

vSphere Network I/O Control

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ChrisFD2
VMware Employee
VMware Employee

As Martin says, no, it is not limited to 40%. What gives you that idea?

Regards,
Chris
VCIX-DCV 2023 | VCIX-NV 2023 | vExpert *** | CCNA R&S
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cyberpaul
Enthusiast
Enthusiast

Never heard of this limitation.

I do believe there is some kind of throttling so that backup or svMotion operations do not have negative impact on your primary workload. But I've never been able to find any documentation regarding this topic.

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Finikiez
Champion
Champion

Veeam says that you can't get more than 40% of bandwith from vmkernel interface if you use NBD trasport method

see https://www.veeambp.com/proxy_servers_intro/proxy_server_vmware-vsphere/transport_modes/network_mode...

  • 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.
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ChrisFD2
VMware Employee
VMware Employee

The throtteling mechanism is mention above - Network I/O Control.

Regards,
Chris
VCIX-DCV 2023 | VCIX-NV 2023 | vExpert *** | CCNA R&S
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Finikiez
Champion
Champion

It isn't AFAIK.

Or is there any prove? Smiley Happy

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cyberpaul
Enthusiast
Enthusiast

I don't think it is. Network IO control applies to distributed switch only, whereas the NFC throttling is clearly present on standard switches as well.

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