Don’t uninstall to fix Exchange!

Exchange Server does, occasionally, act oddly.  Alright, it can do that a lot, but hopefully you won’t run into the phenomenon.  If you should see strange behavior from your Exchange Server, the first thing to remember is that it is not a truly stand-alone application, and can’t be treated as such.  When problems happen with many software packages, the default fix-it is to uninstall the applications, reboot and reinstall.  While that may work with many apps on the Windows Server platform, doing that for Exchange Server will lead to rather disastrous results.

When Exchange Server installs, one of the first things it does is start building structures in Active Directory.  If you have no Exchange Servers at all, this includes extending the Schema and creating an Organization for Exchange and the related security constructs in both the Forest Root domain and the domain you’re installing into.  The thing many folks don’t realize until it is too late, is that much of this mucking about in Active Directory is undone when you uninstall an Exchange Server, which could be a problem if you plan on just fixing something and moving on.

When you uninstall Exchange Server, the uninstallation protocol will remove all objects in AD that were assigned to that server, which could lead to unexpected end results for users, Public Folders and other objects that don’t exist elsewhere in your organization.  This means that an attempt to uninstall to fix a somewhat minor issue could result in an absolute disaster for your Exchange environment overall that cannot be fixed by simply failing over.  The Organization and Forest Root updates will remain, but most of what you did in terms of configuration for the specific Exchange Server will be wiped out.

So, what to do in order to avoid this?  First, hit http://technet.microsoft.com and http://support.doubletake.com to see if there are articles on how to fix the problem you’re seeing.  These documents generally detail much easier fixes for common Exchange problems, and not-so-common ones as well.  Correcting the issues with Exchange still in place is the best route to take when it’s available.

If you do have to reinstall Exchange, your best bet is to shut down the malfunctioning server, build a new one with the same name, and use the disasterrecovery or recoverCMS switches with the Exchange Server installer tools.  This will transfer the settings over to the new machine, instead of removing everything permanently from AD.  Nearly all configuration for Exchange is stored in AD, so using these switches during the installation will allow you to get back up and running quickly, ready to restore the mailbox and folder data from an independent backup.  More information on these switches, the exact syntax for each version of Exchange Server and guidelines for use can be found in various places. http://support.microsoft.com, http://www.msexchange.org and http://technet.microsoft.com are three great resources.

As with most other topics, Exchange acts differently from most other applications when it comes to reinstallation. Always check the support sites before you take any drastic measures, and remember that Exchange is a totally AD-integrated application, so you’re never working on “just the Exchange Server itself.”