Anything But Native Mode

I seem to find myself having the same conversations with customers, over and over, regarding the risks associated with raising the functional mode of the domain or forest. I could name (but I won't) 6 customers in the past few years that developed expensive (in hours spent) contingency and rollback plans for moving a domain to native mode. I could name another customer that was okay with moving to Windows 2000 Native mode, but not 2003 (they came from NT 4.0 directly to 2003). 

I believe, therefore, that Microsoft has misinformed customers on this subject. I believe the key phrase is, "Warning: Raising the functional level of this domain is an irreversible process." And, unfortunately, that phrase seems to trump, "To activate the new domain features the administrator can raise the domain functional level."

That's the real key phrase. Existing features do NOT disappear. The only thing that disappears is backwards compatibity with older domain controllers (IE: no more NT 4.0 DCs can be added to the domain). For a complete listing of new features in each of the functional modes, see https://support.microsoft.com/kb/322692/. Interestingly enough, this same article tells you how to devise a backout plan, though I've never seen a case where this was required.

How about you? If you're a customer, stumbling across this page, and you have specifically experienced a problem after upgrading your functionality level, let me know. Tell me what level you were at, what you changed it to, and what broke as a result.

Comments

• Anonymous
  September 06, 2006
  It added an additional six months in our domain to move to Exchange 2000 Native because of the "irreversible" status (management refused to sign off because there wasn't a backout plan...)
  
  Within three months of getting to Native, we migrated to Exchange 2003 mixed...