Obtain key values for shared-memory segments

The values of the SERVERNUM configuration parameter and shmkey, an internally calculated number, determine the unique key value for each shared-memory segment.

To see the key values for shared-memory segments, run the onstat -g seg command. For more information, see the sections on SHMADD and the buffer pool in your IBM® Informix® Performance Guide.

When a virtual processor requests that the operating system attach the first shared-memory segment, it supplies the unique key value to identify the segment. In return, the operating system passes back a shared-memory segment identifier associated with the key value. Using this identifier, the virtual processor requests that the operating system attach the segment of shared memory to the virtual-processor address space.