Working with Named and Multiple Instances of SQL Server (64-bit)
This topic applies only to SQL Server 2000 (64-bit).
With Microsoft® SQL Server™ 2000 (64-bit), you have the option of installing multiple copies, or instances, of SQL Server on one computer. When setting up a new installation of SQL Server 2000 or maintaining an existing installation, you can specify it as:
- The default instance of SQL Server.
This is the instance of SQL Server that is accessed by supplying the computer name as the name of the SQL Server. An installation does not have to have a default instance. However, if you install multiple instances on a single computer, only one instance can be the default instance. Applications using client software from earlier versions of SQL Server can connect to a default instance.
- A named instance of SQL Server.
A computer can run up to 15 named instances of SQL Server concurrently (16 instances including the default instance), as long as it has sufficient resources to support them. A named instance is identified by the network name of the computer plus an instance name, in the format computername\instancename, where instancename is the name provided for the instance during Setup. Most applications must use SQL Server 2000 client components to connect to a named instance. For naming rules, see Naming Instances (64-bit).
Each instance has its own separate folder for storing the server program files, and the data files for each instance can be placed wherever you choose. Each instance also has its own SQL Server Agent service. The tools for all instances are installed only once.
Multiple instances occur when you have more than one instance of SQL Server 2000 (64-bit) installed on one computer. Each instance operates independently from any other instance on the same computer, and applications can connect to any of the instances. The number of instances that can run on a single computer depends on resources available. The maximum number of instances supported in SQL Server 2000 (64-bit) is 16.
A named instance of SQL Server 2000 (64-bit) can be installed at any time: before, after, or instead of installing the default instance of SQL Server 2000 (64-bit). When you install SQL Server 2000 (64-bit) on a computer with no existing installations of SQL Server, Setup specifies the installation of a default instance. You can choose to install SQL Server 2000 (64-bit) as a named instance by choosing the Named Instance option in the Instance Name dialog box.
Each named instance is made up of a distinct set of services and can have completely different settings for collations and other options. The directory structure, registry structure, and service names all reflect the specific instance name you specify.
Service Names for Default and Named Instances
When you install a default instance of SQL Server, the service names are MSSQLServer and SQLServerAgent.
When you install a named instance of SQL Server, the service names are changed to:
- MSSQL$instancename for the MSSQLServer service.
- SQLAgent$instancename for the SQLServerAgent service.
The Microsoft Distributed Transaction Coordinator and Microsoft Search services are installed only once, and can be used simultaneously by every installed instance of SQL Server.