Very slow network performance in ESXi 5

[CompleteNetwork]

We recently upgraded one of our servers from ESXi 4.1 to 5. It is a Dell PowerEdge T300 with 24GB RAM. It used to run very fast but after the upgrade the network is very slow. We have another server that still runs ESXi 4.1 that runs very fast.

I notice the network slowness in both Windows 7 and Windows 2008 R2 systems. When I copy a file from the ESXi 5 hosted VM to a physical machine on our network, I get between 2-4 Mbps. When I copy from the ESXi 4.1 hosted VM to the same physical machine, I get 80Mbps.

I've tried disabling TCP offloading on both the physical machine and the virtual machines (and both) with no improvement.

I've also performed a WireShark packet capture on one of the Win 7 VMs. One interesting thing I noticed is that there were a lot of Duplicate ACK packets when transferring a file over SMB. I wasn't sure where to go from there.

If anyone has any suggestions, I'd appreciate it.

[GregecSLO]

Hi!

Have you tried change adapter in VM?

You have E1000 or VMXNET3?

Try both if any changes.

Your system IS on HCL so there should be no problems with network card drivers...

Regards,

Greg

[CompleteNetwork]

Thanks for the suggestion. I tried both drivers and there is no improvement in network speed. I tried disabling all offloading options in the VM with both drivers. No improvement. Still seeing between 2-4 Mbps for network speed.

[GregecSLO]

Hi!

What speeds are you seeing here (screenshot)?

Regards,

Greg

[CompleteNetwork]

I'm seeing 100 Full, which is what I expect. I have it connected to a 100Mbit switch.

I see the same thing on my ESXi 4 server and I'm getting very good network speed on those VMs (80Mbps)

[GregecSLO]

Have you maybe enabled traffic shaping policy on vSwitch settings?

Just to be sure... This is new install of ESXi 5.0 with defaults loaded and that is it?

If so, contact VmWare support, maybe this is driver issue...

[CompleteNetwork]

Traffic shaping is not enabled.

This was an upgrade from ESXi 4.1 to 5 with the default settings.

I will probably open a ticket with VMWare. Thanks for the help.

[nirvy]

Have you checked speed/duplex on both ends?

[CompleteNetwork]

Yes I have. It's set to 100 Full at both ends.

After the upgrade, it was set to Auto and set itself to 10 Half. I manually changed it to 100 Full, which improved things a bit but didn't get me the speeds I was expecting.

[kjb007 · Accepted solution]

Check the BIOS on the ESXI 5 server, and see if that physical NIC is sharing IRQ's with another device, and change it if it is.

-KjB

[CompleteNetwork]

That was it! Thank you. I don't understand why it wasn't causing a conflict when we had ESXi 4.1 on the system but I'm very happy to have it working.

[cylent77]

Kanuj Behl wrote:

Check the BIOS on the ESXI 5 server, and see if that physical NIC is sharing IRQ's with another device, and change it if it is.

-KjB

i dont understand how you can do that these days with the new efi based bioses like mine on an asus p67 motherboard. it simply doesnt show irqs anymore ..