Slow Network for VM2 but fast for VM1

[ITTropolis]

Hi:

I have a server running ESXi 5.5 with (2) VMs:

VM1: Virtual Machine Version 8, Windows Server 2012 R2 Standard, E1000E network adapter

VM2: Virtual Machine Version 10 vmx-10, Windows Small Business Server 2011 Stadard, E1000 network adapter

Both VMs are on the same VMNetwork and both are showing network adapters connected at 1Gbps.

If I run an Internet speed test from VM1, it comes back around 500 Mbps (customer has fast fiber Internet connection)

If I run an Internet speed test from VM2, it comes back at only 15 Mbps

Any ideas as to why VM2 connects to Internet so much slower?

Thank you!

Bob H.

[daphnissov]

You should not be using any of the E1000* adapter types with those VMs. Add VMXNET3 and reconfigure the guests to use them. Remove the E1000* adapters.

[mguidini]

I believe you should approach this matter in different layers.

- First as our colleague mentioned, use the VMXNET3 adapter, along with the recommended/updated vmtools version.

- Second, try to isolate the issue from the host perspective: VMs are in the same host? Going through the same vSwitch/portgroup and vmnics?

- Even though they are in the same portgroup "VMNetwork" as you mentioned, use the command #esxtop + option "n", and check if the VMs are using the same vmnic.
- Try different vmnics by migrating the VM to a different host, check the vmnic drivers.

- Lastly consider that you might be facing an issue outside the VMware world, most probably a physical issue or even a GuestOS issue.

Hope that helped.

Regards,

[ITTropolis]

Hi:

Both VMs are on same physical host and both are using the same vmnic0.  I added the VMXNET 3 adapter to the slow VM and removed/disabled the E1000 adapter but it's Internet speed is still much slower than the other VM.  The VMXNET 3 adapter shows it's connected at 10GB/s.

I did notice in vSphere settings for the VMXNET 3 adapter that it said the DirectPath I/O is Inactive and that I need to select Resources tab and to reserve all the guest memory, which I did.  However, it still shows DirectPath I/O as Inactive with message that "The state of the attached network prevents DirectPath I/O."  See attached screenshot.

Any further ideas?  The slow vm is Windows SBS 2011 and the fast vm is Windows Server 2012 R2.  Could guest OS be the issue?  I don't think so, ya?

Thanks so much for any insights!

Bob H.

mguidini​

daphnissov​

[ashishsingh1508]

I stopped reading after 5.5.

No longer under support.

[mguidini]

Humm.. SBS 2011, try the following:

Check from the windows command prompt, RSS and TCP Chimney offload, if it's enabled, disable both:

Check:

netsh int tcp show global

Disable:

netsh int tcp set global chimney=disabled

netsh int tcp set global rss=disabled

https://support.microsoft.com/en-us/help/951037/information-about-the-tcp-chimney-offload-receive-side-scaling-and-net

Check again the network throughput if it gets any better...These features were supposed to help, but in virtualized environments they are always making trouble..