 |
|
Oracle Tips by Burleson |
Oracle 10g Shared Server Configuration
In shared server architecture, the listener
assigns each new client session to one of the dispatchers. As the
user makes requests, the dispatcher sends the request to the shared
server. It is also possible that a different set of shared servers
are utilized for a given user session. The dispatchers act as the
coordinating agents between the user sessions and the shared
servers.
A dispatcher is capable of supporting multiple
client connections concurrently. Each client connection is bound to
a virtual circuit. A virtual circuit is a piece of shared memory
used by the dispatcher for the client connection requests and
replies.
An idle shared server process picks up the
virtual circuit from the common queue, services the request, and
relinquishes the virtual circuit before attempting to retrieve
another virtual circuit from the common queue. In this way, a small
number of server processes are able to service a large number of
clients or users. This method also supports an increased number of
users with less system resources.
Note that not all applications are certified to
use shared servers, but that server-side load balancing in a RAC may
benefit from using shared servers.
As seen in
Figure 9.5, the listener communicates with the dispatchers on
behalf of the user or client sessions. Once the user sessions
establish connectivity with dispatchers, the shared servers service
them.
Prior to the release of Oracle Database 10g,
you needed to set up at least one dispatcher for the shared server
configuration to be enabled. You normally needed to set the
dispatchers initialization parameter to configure the information
about dispatchers.
With Oracle Database 10g, even without
specifying a dispatcher with the dispatchers parameter, you can
enable shared server by setting shared_servers to a nonzero value.
The default behavior is that Oracle creates one dispatcher for the
TCP protocol automatically. This way, it is easier to configure a
shared server environment.
The equivalent dispatchers initialization
parameter for this configuration would be:
Get the complete Oracle10g story:
To get the code instantly, click here:
Need an Oracle Mentor?
BEI is now offering personal mentors for Oracle DBAs where you can have an
Oracle expert right at your fingertips, anytime day or night. We work with
hundreds of Oracle databases every year, so we know exactly how to quickly
assist you with any Oracle question.
Why risk an unplanned outage? You can now get telephone access to Don
Burleson or any of his Oracle Certified DBAs with more than 20 years of
full-time IT experience. Click here for details:
http://www.dba-oracle.com/service_oracle_backup.htm
|
