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.
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.
I stopped reading after 5.5.
No longer under support.
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!
Humm.. SBS 2011, try the following:
Check from the windows command prompt, RSS and TCP Chimney offload, if it's enabled, disable both:
netsh int tcp show global
netsh int tcp set global chimney=disabled
netsh int tcp set global rss=disabled
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..