When launching Exchange Server 2010 setup you may encounter this error message.
The Exchange Server is in an inconsistent state. Only disaster recovery mode is available. Please use Setup /m:RecoverServer to recover this Exchange server.
This can occur when the Exchange server object already exists within Active Directory, which can occur when a server has been uninstalled and you are attempting to reinstall it.
If you do not wish to use disaster recovery mode to reinstall the server you must first remove the Exchange server object from Active Directory.
Launch ADSIEdit.msc and navigate to CN=Configuration, CN=Services, CN=Microsoft Exchange, CN=<Your Organization Name>, CN=Administrative Groups, CN= <Exchange 2010 Administrative Group>, CN=Servers, CN=<Server Name>, and then delete the server object.
In this example screenshot the server name is EX2.
After deleting the object you may need to wait for the change to replicate throughout Active Directory. Then you can relaunch Exchange setup and proceed with your installation as planned.