In Windows Server 2008 R2 Hyper-V R2, when a running or a saved state virtual machine is migrated to another server, the destination server may have a processor with a different set of features. An operating system or application that attempts to execute CPU features discovered when the virtual machine was started on a "source" machine, but not present on the destination (called "destination") machine, will cause a virtual machine migration failure.
The Hyper-V R2 virtualization platform prevents the migration of a virtual machine that will fail in this way because the processors of the "source" and "destination" servers are not compatible. However, this check for compatibility only happens at the time of virtual machine migration, not when the server joins a cluster.
Windows Server 2008 R2 includes a capability called “Processor compatibility mode” so that you can avoid the situation where virtual machines cannot be migrated due to processor incompatibilities. However, if you do not want to turn this capability on for each of your virtual machines, you can use this wizard to identify which machines in your environment are compatible.
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