Tuning the Enterprise Server for
For more information on configuring the load balancer
HADB timeouts
The sql_client time out value may affect performance.
Operating System Configuration
If the number of semaphores is too low, HADB can fail and display this error message:
No space left on device
This can occur either while starting the database, or during run time.
To correct this error, configure semaphore settings. Additionally, you may need to configure shared memory settings. Also, adding nodes can affect the required settings for shared memory and semaphores. For more information, see “Configuring Shared Memory and Semaphores” in Sun GlassFish Enterprise Server 2.1 High Availability Administration Guide.
Tuning the Enterprise Server for High-Availability
This section discusses how you can configure the high availability features of Enterprise Server. This section discusses the following topics:
■“Tuning Session Persistence Frequency” on page 117
■“Session Persistence Scope” on page 118
■“Session Size” on page 118
■“Checkpointing Stateful Session Beans” on page 119
■“Configuring the JDBC Connection Pool” on page 119
■Descriptor configuration in the web application
To ensure highly available web applications with persistent session data, the high availability database (HADB) provides a backend store to save HTTP session data. However, there is a overhead involved in saving and reading the data back from HADB. Understanding the different schemes of session persistence and their impact on performance and availability will help you make decisions in configuring Enterprise Server for high availability.
In general, maintain twice as many HADB nodes as there are application server instances. Every application server instance requires two HADB nodes.
116 | Sun GlassFish Enterprise Server 2.1 Performance Tuning Guide • January 2009 |
