Managing Multiple Instances of Analysis Services
Other than sharing the same computer hardware resources, each instance of Microsoft SQL Server 2005 Analysis Services (SSAS) is completely independent, with independent executables, properties, security models, databases, cubes, and so on. Each instance can be stopped and started independently. Having multiple instances of Analysis Services on a single computer can provide many benefits, including the ability to test applications, fixes, and service packs on a secondary instance on the same computer before you implement them on the primary instance, and to run applications on separate instances with different server configuration properties. However, as all instances on a single computer share the same memory resources, instances that exist only for testing purposes should be configured to start manually in order to conserve memory for the primary instance.
Each instance of Analysis Services must also have its own port through which clients can connect. This port can either be manually assigned by an Analysis Services administrator or selected dynamically by Analysis Services at startup from the first port available. Regardless of whether the port is manually or dynamically configured, Analysis Services clients are required to have to be able to identify and connect to the port associated with the appropriate instance of Analysis Services.
Defining the Port on Which Analysis Services Instances Listen
The Port server property for an instance of Analysis Services determines the port number on which the instance listens for client connections. The Port property has a default value of 0. This means that the instance uses the default port, 2383. An Analysis Services administrator can change the default port value to a specific port number or can leave the default value as is. If set to the default value, the instance tries to use the default port, 2383. If the default port is already used by another instance, Analysis Services picks the first available port from a dynamic range of ports and assigns this port to the instance. Analysis Services also records the port number and the instance name with SQL Server Browser, which is the service that handles lookup of named instances.
To information about how to change the Port server property, see Setting Server Configuration Properties
Configuring How Clients Locate Analysis Services Instances
Unless an Analysis Services client specifies a port number, the client tries to connect to the instance of Analysis Services on port 2383. If an Analysis Services client wants to connect to a named instance of Analysis Services that is listening on another port number, then the client either has to specify the exact port being used by the named instance, or is directed to the Analysis Services redirector service on port 2382. The Analysis Services redirector service is part of SQL Server Browser and maintains a record of the port number for each instance of Analysis Services that is running on the computer. The redirector service redirects client requests from port 2382 to the appropriate port for the named instance.
If an Analysis Services client will be connecting over the Internet to an Analysis Services instance that is running on a dynamically assigned port, either port 2382 must be open on the firewall so that the client can to connect to the SQL Server Browser to be redirected to the named instance, or the port that is used by the named instance must be open on the firewall and the client must be configured to connect directly to this port.
Although SQL Server Browser knows the port assigned to each instance of Analysis Services, an instance can be hidden from clients that do not supply the specific port number for the instance. To hide an instance, set the InstanceVisible server property to 0. When the InstanceVisible server property is set to 0, SQL Server Browser will not connect a client to a named instance if the client does not specify a specific port number. For more information about how to change the InstanceVisible server property, see Setting Server Configuration Properties.
|Regardless of whether a client has permissions for any Analysis Services instances on a computer, a client can query SQL Server Browser for a list of available instances on that computer. The list supplied by SQL Server Browser includes all available instances, except those instances that have been hidden.|