There are a few warning messages that can “sort of” be ignored when upgrading to Server 2008 R2. The compatibility checker is quite good at stopping you if you absolutely shouldn”t continue, but there are also some warnings that might seem puzzling.
If your server has the Hyper-V role enabled, the compatibility checker will tell you to remove the role. You really don”t want to do that, because you”ll lose an awful lot of configuration. What it SHOULD tell you is to make sure that all of your virtual machines are in an off state, because the saved state is incompatible with the new Hyper-V. If this is the case, you can safely ignore this warning and click next.
If you have SharePoint Server on the machine, the advisor will tell you to remove it. Again, this isn”t something that you”re going to want to do. What the advisor should REALLY be telling you is that All versions of SharePoint prior to 2007 with Service Pack 2 are incompatible with Server 2008 R2. If this is the case, or you”re simply unsure, stop the upgrade, and go apply Service Pack 2. Then (and only then) can you safely ignore the message, and continue the upgrade.
One last potential gotcha – after upgrading,your server will need to be reactivated. The upgrade process doesn”t tell you that.
The upgrade process appears to work rather well – so far I haven”t yet encountered any problems.