SQL error log finds all copies of resource db after moving db

Just a short post about something interesting I saw in the SQL error log a while back.

A while ago, I moved the system databases off the C drive’s of our servers to another drive on the SAN. That included moving the resource database. You can read Microsoft’s recommendations on moving system db’s on MSDN.

Anyway, I copied the mssqlsystemresource.mdf and mssqlsystemresource.ldf files to a backup location in case of an emergency. But only one database was attached. 

This interesting entry in the SQL error log was after I restarted the server:

The resource database has been detected in two different locations. Attaching the resource database in the same directory as the master database at 'O:\SQL2005\DATA\master.mdf' instead of the currently attached resource database at 'O:\SQL2005\Data\mssqlsystemresource.mdf'.

So, SQL saw both the attached db and the unattached backup copy when I restarted the service. The only time I saw the message was the first reboot, not any subsequent restarts.