Why does SQL Server have multiple instances?

Can a SQL Server have multiple instances?

Yes, we can use multiple instance of SQL Server of same machine/server. All instances of the database engine other than the default instance are identified by an instance name specified during installation of the instance.

How many instances can a SQL Server have?

You can install as many as 50 SQL Server instances on a Windows Server; obviously, we do not recommend this. In a Windows failover cluster, the maximum number of SQL Server instances is reduced by half if you're using shared cluster drives. Only one of the SQL Server instances on a server can be the default instance.

What are some of the benefits of using multiple and separate instances of SQL Server?

A second area in which multiple instances provide great benefit is server consolidation. Instead of having 10 machines to run 10 applications, a company can run all applications on one machine. With separate SQL Server instances, each application can still have its own administrator and its own users and permissions.

What are SQL Server instances?

An instance of the Database Engine is a copy of the sqlservr.exe executable that runs as an operating system service. Each instance manages several system databases and one or more user databases. Each computer can run multiple instances of the Database Engine.