Use this page to select the connection mode for the database. The modes you can select from are:
Dedicated Server Mode
This topic describes these two modes of database operation, when you should select Shared Server mode, how to select the proper number of shared server processes, and how to customize the default shared server parameters.
An Oracle Database in the dedicated server mode requires a dedicated server process for each user process. There is one server process for each client. Oracle Net sends the address of an existing server process back to the client. The client then resends the connect request to the server address provided. Contrast with Shared Server.
Select the Dedicated Server Mode when:
You are using your database in a Data Warehousing environment
The number of total client connections is expected to be small
Database clients will be making persistent, long-running requests to the database
An Oracle Database in the shared server mode (also known as multi-threaded server mode) is configured to allow many user processes to share very few server processes, so the number of users that can be supported is increased.
Without a Shared Server, each user process requires its own dedicated server process. With the Shared Server configuration, many user processes connect to a dispatcher. The dispatcher directs multiple incoming network session requests to a common queue. An idle shared server process from a shared pool of server processes picks up a request from the queue. This means a small pool of server processes can serve a large number of clients.
Select the Shared Server Mode when:
You are using your database in an Online Transaction Processing (OLTP) environment. On-Line-Transaction-Proces using applications benefit substantially by using the Shared Server.
A large number of users need to connect to the database, and efficiently use the available system resources.
You have memory constraints. Shared Server reduces the total memory usage as the number of users increases, as compared to dedicated servers. In the latter mode the memory consumed increases almost proportionately to the number of users. Shared Server allows you to tune and optimize overall system performance, so if a high degree of control over tuning the database is an important criterion, then you may want to use a Shared Server.
You want to use Oracle Net features such as connection pooling, connection concentration, and load balancing.
You are managing and utilizing system resources to a high degree, and this is an important criterion.
Predictable and fast connection times are very important, for example, for Web applications.
Note: Even when the Shared Server is enabled, certain kinds of functionality, such as administrating the instance, need dedicated servers. In such cases, use dedicated connections.
Use the Shared Server field to specify the number of shared servers that you want started. Thereafter, Oracle dynamically adjusts the number of shared servers based on the length of the request queue.
In typical systems, the number of shared servers seems to stabilize at a ratio of one shared server for every ten connections. For OLTP applications, the connections-to-servers ratio could be higher. This might happen when the rate of requests is low, or when the ratio of server usage to request is low. On the other hand, in applications where the rate of requests is high, or the server usage-to-request ratio is high, the connections-to-server ratio could be lower.
The actual number of server processes at any point in time will vary and will be dynamically adjusted between this number and the "Max no. of server processes" specified on the Edit Shared Server Parameters page. At no point will the number of sever processes go below this number, even if the load is very low.
For complete information about determining the number of initial shared servers, as well as information about changing this setting after you have created the database, see the chapter "Managing Oracle Processes" in the Oracle Database Administrator's Guide.
When you enable Shared Server mode, you can use the default settings, or you can customize a set of shared server parameters. To edit the default settings, click Edit Shared Server Parameters. Click Help on the Edit Shared Server Parameters page for more information.
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