Setting Operating-System Shared-Memory Configuration Parameters

Several operating-system configuration parameters can affect the use of shared memory by the database server.Parameter names are not provided because names vary among platforms, and not all parameters exist on all platforms. The following list describes these parameters by function:

• Maximum operating-system shared-memory segment size, expressed in bytes or kilobytes
• Minimum shared-memory segment size, expressed in bytes
• Maximum number of shared-memory identifiers
• Lower-boundary address for shared memory
• Maximum number of attached shared-memory segments per process
• Maximum amount of systemwide shared memory
• Maximum number of semaphore identifiers
• Maximum number of semaphores
• Maximum number of semaphores per identifier

On UNIX, the machine notes file contains recommended values that you use to configure operating-system resources. Use these recommended values when you configure the operating system. For information on how to set these operating-system parameters, consult your operating-system manuals.

For specific information about your operating-system environment, refer to the machine notes file that is provided with the database server.

You can also tune certain shared-memory configuration parameters on the fly using the onutil SET command. Changes made with this utility do not require a server restart, but instead take effect immediately.