SQL Server installations and databases (explained)
The management server, the event server and the log server store, for example, the system configuration, alarms, events and log messages in SQL Server databases on one or more SQL Server installations. The management server and the event server share the same SQL Server database while the log server
The system installer includes Microsoft SQL Server Express which is a free edition of SQL Server.
For very large systems or systems with many transactions to and from the SQL Server databases, Milestone recommends that you use the Microsoft® SQL Server® Standard or Microsoft® SQL Server® Enterprise edition of SQL Server on a dedicated computer on the network and on a dedicated hard disk drive that is not used for other purposes. Installing SQL Server on its own drive improves the entire system performance.