We recently received the question in terms of the TFS Migration Tools “Can I migrate from TFS 2008 to TFS 2010”, for which the answer was easy: Yes.
The next not so obvious question we received was “Can I migrate from TFS 2010 to 2008”. It is not so obvious as you would probably not migrate from 2010 to 2008, however, you may want to synchronise a TFS 2008 server with a TFS 2010 server, which kind of entails a 2008—>2010 and a 2010—>2008 synchronisation.
The answer to the latter question is also Yes, but with a feature parity mismatch. TFS 2010 supports hierarchical work items, whereas TFS 2008 does not. Moving from 2008 to 2010 is therefore not a problem, however, when we move from 2010 to 2008 the feature parity mismatch raises its ugly head.
We now have a problem or rather challenge that the adapters handle as well as they can. When adapters are loaded and introduced to the pipeline session, they announce their capabilities and negotiate down to the common subset. In terms of the hierarchical work items it means the the “hierarchy” bits are gobbled up on their way from 2010 to 2008, whereby the links are not touched on the 2010 environment.
This is one of the scenarios that Bill’s team are testing as part of their dogfooding!