When attempting to remove a Public Folder Database in Exchange 2010 you receive the following error message below: MapiExceptionMdbOffline: Unable to determine if the store has local replicas (hr=0x80004005, ec=1142).
In my case this Public Folder Database was only a replica on a mailbox server which we had set to decommission. I was unable to mount or remove this PF Database via Powershell or EMC.
One method is to remove the Public Folder Database with ADSIEdit. First, take a backup of your Active Directory environment. Then open ADSIEdit from your primary DC and go to the following location. Configuration: CN=Configuration, DC=domain, DC=com; CN=Services; CN=Microsoft Exchange; CN= Domain name; CN=Administrative Groups; CN=Exchange Administrative Group; CN=Databases; CN=PublicFolderDatabaseName
After removing the Public Folder Database restart the Information Store, the Public Folder Database will be removed.