I have a Microsoft SQL 2005 SP3 database server with 2 instances (both patched to SP3.)
The one instance (1a) includes 52 small production databases.
The other instance (1b) includes 2 large production databases.
Now I would like to upgrade the (1b) instance to the new Service Pack 4.
The way I would to this is the same way as I would do it with Service Pack 3: http://www.db-staff.com/index.php/microsoft-sql-server/87-upgrade-sql-2005-cluster-to-sp3
But... If I do this and things go wrong, I can not uninstall the Service Pack 4...
Do you have any experience regarding Service Pack 4?
And do you have any proposal to what I can do?