The VMMCA, or Virtual Machine Manager Configuration Analyzer (VMMCA) is a diagnostic tool you can use to evaluate important configuration settings for computers that either are serving or might serve VMM roles or other VMM functions. The VMMCA scans the hardware and software configurations of the computers you specify, evaluates them against a set of predefined rules, and then provides you with error messages and warnings for any configurations that are not optimal for the VMM role or other VMM function that you have specified for the computer.

When should I use the VMMCA?

Before installing VMM, you can use the VMMCA to help you evaluate the configuration of computers that you might use for the following VMM roles:

• VMM Server
• VMM Administrator Console
• VMM Self-Service Portal

After installing VMM, you can use the VMMCA to evaluate the configurations of computers that you are now using or might use for the VMM roles listed above, as well as computers that you are using or might use for any of the following VMM functions:

• Windows Server–based host
• VMware Virtual Center Server (or vCenter Server) 
• P2V source computer
• Operations Manager agent

In what kind of situations is it useful to use the VMMCA?

1. Before you add a server as a managed host.

2. Before you add a server as a library server.

3. Before you try to perform a P2V conversion.

4. Anytime you're troubleshooting a host that is in the “not responding” state in the console.

5. Any time there's a communication issue between the VMM server and another component.

Where can I get the VMMCA?

Download the System Center Virtual Machine Manager 2008, 2008 R2, and 2008 R2 SP1 Configuration Analyzer

(Before you install the VMMCA for VMM 2008, 2008 R2 or 2008 R2 SP1, you must download and install the 64-bit version of Microsoft Baseline Configuration Analyzer (MBCA). Download the MBCA.)

Download the System Center 2012 - Virtual Machine Manager Configuration Analyzer

(Before you install System Center 2012 - VMMCA, you must download and install the MBCA 2.0. Download the MBCA 2.0.)

How to manually update the list of KB articles that are checked (applies to the System Center 2012 - VMMCA):

If you are running the System Center 2012 - VMMCA in an isolated environment, you can use the following procedure to update the KB checker file:

1. Download the file VMMCA_KBCheck_KBList.cab from the Download Center.
2. Navigate to the folder where you saved the .cab file.
3. Double-click the saved VMMCA_KBCheck_KBList.cab file, and then double-click the VMMCA_KBCheck_KBList.ps1 file to extract the PowerShell script file.
4. In the Select a Destination dialog box, select the folder where you want to extract the file. 
5. Copy the extracted VMMCA_KBCheck_KBList.ps1 file to C:\ProgramData\Microsoft\Microsoft Baseline Configuration Analyzer 2\Models\SC2012VMMCA\VMMCA_KBCheck.
6. Copy and replace the existing file.

Conclusion

The VMMCA has proven itself to be an invaluable resource when troubleshooting VMM issues and has helped me quickly resolve many complex issues.  I strongly encourage you to download and try it out.

Note: This information (without the 2012 info) was originally provided by Mike Briggs, Senior Support Escalation Engineer, on the System Center Virtual Machine Manager Team blog:

http://blogs.technet.com/scvmm/archive/2010/01/27/the-vmmca-and-why-it-s-important-in-troubleshooting-vmm-issues.aspx