One of the areas I found most likely to trip you up in a Windows 2003 DC upgrade is the area of application compatibility. It's really hard to know what's out there in your environment, and to plan for it. Since your domain controllers service all kinds of applications on servers in your Active Directory forest, unless you have a really buttoned-down environment, you probably don't have a handle on the apps that are touching your DC's. For example, when's the last time you talked to your network operations group about the software they use for managing their routers? Microsoft talks a good deal about Windows client compatibility, but says very little about non-Windows clients.
I'd like to hear from you - if you upgrade to Windows 20003, or you're in the middle of an upgrade, what kind of application compatibility issues have you come across?
- Sean
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Normaly something like this wouldn't bother me but like most enterprises there were multiple builds and configurations, and the deployment plan was a phased one which meant I had to ensure that everything was leveled out before I begin the upgrade. This meant that, without any sort of management tools in place, I had to deploy SP6a to everything, patch NT(SE) because the service pack defaults back to the Microsoft GINA and apply a 'compatibility' kit to allow AD translation between the clients & the PDC. There were a few other tweaks as well but that was the bulk of it.. and I managed to do it all remotely without any patch systems or management servers as well!
The one big problem I had was with WTS, Terminal Server. After applying all the relivant updates etc none of the TS clients could authenicate to the domain so after a few hours of poking about I had discovered that the updates hadn't written a registry key to allow the clients to use the encrypted GINA values.
Lessons learnt; make sure to bring all clients and servers level with one another, this will hours if not days of screaming and swearing when you're trying to track down an application fault. Also, look to see what is being modified if any application patches or updates are needed. You have the luxuary that NT4 applications are generally not as complex as their AD-aware counterparts so looking to see what it's doing, comparing it with whats supposed to happen helps address the problems quickly when the updates don't work ie. missing registry keys!
sgaw January 16, 2005