Installing SQL Server DB Engine 2005 AND 2008R2 in the same box with same instance name?

1

Hello everyone,

Some how I could have swear I have done this in the past, apparently I am wrong.
I came to a contract that has windows server 2008 R2 with SQL Engine 2005 sp4 (9.00.5000) and I was asked if possibly I could installed SQL engine 2008 R2 with the same instance names (2 instances). Their thought is to transition between 2005 and 2008 R2 for testing, once satisfied we'll get rid of 2005.
As I mentioned, I thought there was no problem in doing this... that is concurrently having the 2 versions with the same instance names.
While doing my test I found an error during the 2008 R2 Enterprise edition stating 'validation error on the page. Review errors at the botom of the setup page...'of course I do not see errors on the setup page. But I do add a character to the instance name and it goes on through the installation..

Once again I could have swear I've done this in the past (probably with different versions), logically I don't see why it wouldn't work since the path directories are based by numbers (sort of like Oracle's Home).
Can anyone tell me why and where am I so wrong and if this was ever possible at all in the pasts??... I am truly surprised!!

Thanks in advance for any prompt replies!!

Sincerely,
lec

2

Actually logically it can't work since the service names used the instance name and thus there would be a duplicate. It has never been the case that you can install two instances with the same name on the same server. On different servers, yes. Same servers, no.

The instance name shouldn't matter to an application though since it should be just a connection string change.

3

I was afraid you were going to say that and I was mixing SQL and Oracle.... Anyway, thank you Tara! as usual you helped clarify certain doubts!!