tcronin 95651 (9/20/2016)
thanks the upgrade path has been clear there are a few unclear articles I have seen which seem to question whether or not you can do an in place edition upgrade on a physical active/passive cluster
I had to do several of them years ago since the company wanted to do in place upgrades. Didn't run into any problems, just did the normal upgrade passive node, failover, upgrade the other now passive node, checking the cluster resources and ownership in the process, etc.
There may be SP requirements, can't remember. Possibly the 2008 needs to be SP2 or 3 to upgrade to 2008R2. Hopefully the vendor is allowing you to be current on service packs so it shouldn't be an issue. But it is doable on a active/passive cluster.
Sue