12. Using the 2.4 kernel with DB2 Version 7.1

The Linux 2.4 kernel changes the default values of some ipc limits. However, the default value for the msgmni is 16, which causes difficulties running DB2 with the default 2.4 kernel ipc parameters. Fortunately, the 2.4 kernel also enables you to change a number of these parameters through the /proc filesystem. With the 2.4 kernel, you do not have to recompile your kernel to experiment with different parameter values.

Configure the msgmni parameter by issuing the sysctl command as root:

bash# sysctl -w kernel.msgmni=128

You can also change values directly in /proc/sys/kernel using the echo command:

bash# echo "128" > /proc/sys/kernel/msgmni

To set the msgmni kernel parameter at boot time, append the following lines to /etc/sysctl.conf:

# Sets maximum number of message queues to 128 # Set this to 1024 or higher on production systems kernel.msgmni = 128

To check the current ipc settings, issue the ipcs -l command:

bash$ ipcs -l ------ Shared Memory Limits -------- max number of segments = 4096 max seg size (kbytes) = 32768 max total shared memory (kbytes) = 8388608 min seg size (bytes) = 1 ------ Semaphore Limits -------- max number of arrays = 128 max semaphores per array = 250 max semaphores system wide = 32000 max ops per semop call = 32 semaphore max value = 32767 ------ Messages: Limits -------- max queues system wide = 128 max size of message (bytes) = 8192 default max size of queue (bytes) = 16384