First published on TechNet on Feb 20, 2012
I recently ran across an unexpected issue regarding LCS 2005, OCS 2007, LYNC 2010 and AD 2008 R2 schema updates. Unfortunately for my client we discovered the issue too late, but hopefully this article will provide you with the necessary understanding and information for you to be forewarned and therefore forearmed.
While the issue is not directly related to this KB article, you should know that if you have already extended your schema for LCS 2005, OCS 2007 or OCS 2007 R2 and you subsequently extend your schema for AD 2008 R2, there is a known issue. See http://support.microsoft.com/kb/982020 for all the details. In short, you’ll have to re-apply the LCS/OCS schema extensions after the 2008 R2 schema extensions.
Since we were updating the Schema for 2008 R2, we needed to do a quite a bit of planning, coordination and change control preparation. Additionally, the customer decided to install the Exchange 2010 and LYNC 2010 schema updates during the same change control window to expedite an upcoming project. We installed the 2008 R2 Schema Updates (adrep /forestprep; adprep /domainprep adprep /RODCprep) without any issue. We followed our plan and of course did all our validation checking, etc. So far, so good, so on to the Exchange schema extensions. Again no issues with Exchange so onto the LYNC 2010 schema updates. This was the “fatal flaw” in our plan although we had no idea at time, which is in fact the reason for this blog post. Our customer as you may remember was running LCS 2005 and they had intended to go directly to LYNC 2010. This made perfect sense at the time so no need to do anything with OCS, just install the LYNC 2010 Schema updates. So we did. That was a decision as they say, we would live to regret. Well O.K., maybe not quite that dramatic, but as you will find out in a minute this innocent, well-meaning decision is causing a lot of agonizing and anxiety for the customer at this very moment.
Editorial Comment: Many administrators I run across these days don’t think twice about schema updates. I think this may be a testament to the reliability and stability Microsoft has developed in AD. While it is rare and very unlikely you will have an issue just remember the bottom line is if something does go wrong with the schema updates and it creates an issue with the Active Directory database, the only real roll-back option is a complete forest recovery. (Sounds like another blog post).
First, let me offer a bit of a disclaimer in that there has been a lot of investigation and follow on research of the following issue that I have not been involved with so the situation may have changed or new information may be available. So as with any information, use this blog as a guide and do you own research and come to you own conclusions.
Several months later the customer was planning their LYNC 2010 upgrade and discovered there is no coexistence strategy between LCS 2005 and LYNC 2010. Without getting into a lot of details, the migration to LYNC 2010 would require an extended outage which was not acceptable to the customers’ business model. The word around was to do an interim update to OCS 2007 to keep coexistence with LCS 2005 and then once migrated to OCS 2007 they would have coexistence between OCS 2007 and LYNC 2010. O.K., so it sounds like some extra work and time but not a show stopper.
As it turns out it is a problem. The problem is that it is not supported to install the OCS 2007 Schema updates once you’ve installed the LYNC 2010 schema updates. This is causing a major issue for this customer while they regroup and try to come up with a workable plan. I know they had been working with some of the really smart people at Microsoft and they may already have come up with a resolution at this time. If I find out the resolution I’ll update the post however there is a relatively simple preventative solution.
As a result, the recommendation would be if you have LCS and are planning to migrate to LYNC 2010, install the OCS schema updates regardless, before you install LYNC 2010. It should not cause any issues and it provides the opportunity to install OCS if for some reason this became necessary. I expect this is not a very likely or probable situation for most of you but if it helps anyone avoid the situation than it was worth the time to write it up.
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