Database administrators might create multiple instances of the same database for different purposes. For example, an organization with an employees database might have three instances: Production instances: Administrators use these instances to contain live data.

Can you have multiple instances to access one database?

A database can be opened (or mounted) by more than one instance, however, an instance can open at most one database.

Can a server have multiple instances?

You can create more than one server instance on your system. Each server instance has its own instance directory, and database and log directories. Multiply the memory and other system requirements for one server by the number of instances planned for the system.