While upgrading to Exchange 2010 SP2 using the GUI, you will come across the error message shown below. This only happens while upgrading the CAS role.

IIS 6 WMI Required for Exch 2010 SP2 Upgrade

The reason is that the CAS requires a new pre-requisite for supporting OWA mini (a new feature in SP2). Hence, either install it using Server Manager (right click “Web Server” and add role service) or Windows PowerShell.

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http://www.howexchangeworks.com/2011/12/iis-6-wmi-compatibility-component-is.html