Q: What's the minimum number of SQL Server instances needed for System Center 2012?
A. Provided the SQL Server environment is sized and architected correctly, it's entirely possible to run all of the System Center components on a single SQL Server (however, if you have international requirements, you might have some colation configuration considerations for components such as Service Manager).
The other requirement for SQL Server is regarding Reporting Services, which normally can't be shared. This means you will need three separate SQL Server Reporting Services instances for
- Service Manager
- Operations Manager
- Configuration Manager