Description

This page details a known issue with VMware Tools 6.0 and the Receive Side Scaling (RSS) feature in Microsoft Windows. This issue applies only if you are using the Microsoft Windows RSS functionality.


 

Issue

Receive Side Scaling (RSS) is a Microsoft function that provides increased network performance on multiprocessor environments in Microsoft Windows 2008 and later. By default, this function is disabled when using the VMXNET3 network adapter on a NIC. However, users can turn on this function and potentially run into the issue described below. For more information on Network Adapters, see Introduction to Cloud Server NICs in MCP 2.0.

VMware has confirmed there is an incompatibility between VMware Tools versions 9.10.0 (vSphere 6.0) through 10.1.5 (vSphere 6.0p05) and the RSS feature available in Microsoft Windows 2008 or later. If the RSS feature is turned on, the Windows Receive Side Scaling (RSS) feature is not functional on virtual machines running these versions of VMware Tools using VMXNET3 network adapters.   This issue is caused by an update for the vmxnet3 driver that addressed RSS features added in NDIS version 6.30 rendering the functionality unusable. It is observed in VMXNET3 driver versions from 1.6.6.0 to 1.7.3.0.

Symptoms

The incompatibility results in the following issues:

  • Cloud Servers running Microsoft Windows 2008 and later with affected versions of the VMware Tools may experience an increase in the rate of “Received Dropped Packets” caused by the fact that all network traffic will be serviced by only one CPU in the Guest.
  • This issue may not be seen in all cases. The dropped packets  occur only if vCPU 0 is overwhelmed and cannot keep up with the rate of the network transmit/receive.
  • This condition results in performance degradation for the applications and services hosted on the affected Cloud Server

Solution

VMware has released a new version of the VMware Tools (10.1.6 or higher) which fixes the issue.

  1.  Updating VMware Tools as described in How to Update VMware Tools on a Cloud Server will address the issue only if the data center location's VMware Hardware Version, which can be identified as described in How do I Identify Hardware Specifications and Capabilities Available in a Data Center Location, is vmx-11 or higher. However, as of October 2017, there are no data center locations running vmx-11 so this method will not currently work.
  2. Alternately, users can download the 10.1.6 or higher version of VMware Tools from VMware's Packages site at https://packages.vmware.com/tools/index.html and follow the instructions below.

How to Download and Install VMware Tools from VMware Packages Site (Option #2 Above)

How to upgrade VMtools in Windows Server to the 10.1.7 version that 

  1. Log into the Cloud Server that needs to be upgraded and download the VMware Tools 10.1.7 ISO from https://packages.vmware.com/tools/releases/10.1.7/windows/VMware-tools-windows-10.1.7-5541682.iso 

  2. Browse to the Windows Folder, and double click on 'VMwareToolsUpgrader".

  3. You will now see a VMware Tools Setup Wizard.


  4. In the Setup Type, Select 'Typical', Click Next.


  5. You will now see an Install VMware tools wizard. Click Install to start the Installation. 

NOTE - Virtual Machine (Windows Guest OS) has to be rebooted for the Installation to be completed.