Can I add a default instance to a named instance install
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Wednesday, September 12, 2012 1:29 PMI've installed my SQL 2008R2 cluster as a named instance and it's working fantastic. I now have a new requirement for a default instance because of unique application requirement. Can I go back and install a default instance if only a named instance has been used so far? Obviously I can only have one "default" instance, but it hasn't been used yet, right? Also just to be sure this new instance can be a different patch level right (ie SQL 2008R2SP1)?
All Replies
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Wednesday, September 12, 2012 1:36 PMModerator
Hello,
Yes, you can. Go ahead.
Just make sure to balance memory usage across instances using “max server memory”.
Hope this helps.
Regards,
Alberto Morillo
SQLCoffee.com- Edited by Alberto MorilloMVP, Moderator Wednesday, September 12, 2012 1:38 PM
- Proposed As Answer by Prashant Jha Sunday, September 16, 2012 10:01 AM
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Wednesday, September 12, 2012 8:21 PM
Yes, there is not issue. You can install default instance after named instance.
But please consider :-
- Properly configure MIN & MAX memory, there may be a case where your both instances need to run on same node. Try to have sum max memory of both instances = total memory on server
- analysis the expected CPU load for both instances, sum expected cpu uage of both instances must be less than 80%
- Keep files of both inctances in diffrent disk drives / mount points
Please click the Mark as Answer or Vote As Helpful if a post solves your problem or is helpful!
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Friday, September 14, 2012 3:20 AM
Hi eschenfe,
Yes, you can add a default instance after a named instance in one node. And As RohitGarg said you should balance those two instances in the same node.
A default instance has a default instance name(MSSQLSERVER) and it captures the computer's name, also uses it as an alias.
Please try to install a default instance as follow:
1. Start installation and select "New Installation or Add Features to an Existing Installation ".
2. Select option button for "SQL Server Feature Installation".
3. Accept default instances feature then NEXT.
4. Option button for “Default instance” then next.
5. Configure the service account and collation in the server configuration, then next.
6. Configure database engine ,then next.
7. Choose install to begin install.
Please refer to:
How to install Server 2008R2: http://msdn.microsoft.com/en-us/library/ms143219(v=SQL.105).aspx.Regards,
Amy Peng
Please remember to click "Mark as Answer" and "Vote as Helpful" on posts that help you. This can be beneficial to other community members reading the thread.
- Edited by Amy PengMicrosoft Contingent Staff Friday, September 14, 2012 3:20 AM
- Marked As Answer by Maggie LuoMicrosoft Contingent Staff, Moderator Thursday, September 20, 2012 2:42 AM

