从命名实例连接到SQL Server默认实例

Question

I am doing a side by side upgrade from 2k8 to 2k12. The original machine is a named instance and the new machine is a default instance. The goal is to not change connection strings from applications.

If I were going from a default instance to a default instance I could change the DNS A record and have it connect. However, the application are storing the connection string as OLDSERVER\\OLDINSTANCE. The A record is only going to change the OLDSERVER name but the connection is still looking for the \\OLDINSTANCE.

Can SQL Server 2012 be configured to have the default instance accept connections when they are made to an instance that does not exist?

Thanks, Chris

Answer 1

I went through this exact process a few weeks ago, and what I found out sadly is that it does not appear to be possible without uninstalling the old instance (which I wanted nothing to do with). Here were some of the many links that I found on the subject and which I imagine you have probably been through as well.

StackOverflow

SQLServerCentral

MSDN

I tried a number of different things on my local and not one of them worked for me. In my case, if I could have upgraded the server (downtime would have happened) I would have done it, but we were going from SQL 2K8 Enterprise to SQL 2K12 Standard so that was not possible either.

I will be interested in seeing if anyone comes up with a way that this can be done outside of an uninstall, but I could not come up with one and everything that I read seemed to back that up. Maybe someday we will get an sp_dropserver/sp_addserver that will change instance names.

Answer 2

A default instance, as far as the client connecting to it is concerned, is the one listening on 1433.

If you install a named instance with the same name on the new server, and then change it's port to 1433, a client would be able to connect using both NEWSERVER\\OLDINSTANCE and NEWSERVER, as long as the browser is running.