mofcomp is a tool provided by Microsoft and integrated with Windows that is used to register WMI classes such as VMware’s Perfmon counters with Windows.  For reasons that we do not entirely understand, but are tracking with a PR, mofcomp is failing during the tools upgrade on some systems.  Ideally a reinstall/upgrade/repair of VMware Tools will force a rerun of mofcomp and register the classes.  But the tools installer is not configured to do this today as a mofcomp failure was not anticipated by the developers that wrote the VMware Tools installer.

The key to the fix is to force mofcomp to run a second time.  This can be done in two ways:

• Uninstall VMware Tools and then reinstall them.  Unlike a reinstall (also called a “repair” or “upgrade”) this will force mofcomp to be run during the second install.  It should work the second time.  If it does not, I would be interested to know.
• Install the counters using the vmStatsProvider executable, which I documented previously.

Sorry for this problem, everyone.  We are tracking this issue and plan to improve the robustness of the installer as soon as possible.

My colleague in product management, Praveen Kannan, has been working to extend Perfmon to show some ESX performance counters. This capability is automatically installed with VMware Tools on vSphere 4. But Praveen and I have made a stand-alone version available to those of you that are still on VI3. Download it here to give it a try.  [See note below if that link is dead.]

To install, place the file in an appropriately-named directory on any Windows VM on VI3. Double-click the executable, which will self-extract the files into the same directory. Run “install.bat” and you’re done.

Once you bring up Perfmon you’ll see two new performance objects on your computer: “VM Memory” and “VM Processor”. These objects contain counters exposed by ESX that accurately reflect the VM’s memory and CPU usage. Here’s Perfmon on my test VM after I’ve installed the tool.

This makes collection of host stats a breeze. Windows Management Instrumentation (WMI) programs can now easily get access to reliable host statistics. And anyone with access to Perfmon can get see their VM’s resource usage. Unlike guest-based statistics, the host-statistics shown through these counters accurately reflect resource usage in the presence of virtualization overheads and time slicing of VMs.

Disclaimer:

This is a pre-release “sneak peak” version. Eventually this tool will be available for download on vmware.com and supported by VMware. But today there is no support for this tool and you’re using it “as-is”. Use at your own risk and do not contact VMware support for help with this release.

That’s VMware’s official position on this tool. But feel free to comment here with any ideas about this great new feature.

If the Download Link Is Dead

Until the DLL is made available as a standalone product, we are hosting it on the VMware FTP server, which is swept regularly.  If the link is dead that means that the binary has been deleted to save space.  Leave me a comment here if you see this and I will again upload the binary for download.