Q and A

Asked and Answered

I have some questions about DB2 and Linux:

1. What Linux kernel parameters need to be tuned for DB2 on Red Hat Linux Professional 7.2, 7.3/Advanced Server 2.1?

2. What files compile DB2 stored procedures on Linux? When I compile a stored procedure, DB2 generates a package Pnnnnnnn, but I don't want a system-generated package name. I want to name the package myself.

Paul Zikopoulos, IBM Canada, responds:

1. The answer depends on what version of DB2 you are running (or will be running).

In DB2 v.8: Before installing DB2, you may want to update certain Linux kernel parameters. DB2 will automatically raise the IPC limits where necessary. You may still want to raise these limits depending on your particular needs. Of course, you must have root authority to modify kernel parameters.

For Red Hat distributions, any system using the 2.4. x kernel has a default value for the message queue parameter ( msgmni ), which allows only a few simultaneous connections to DB2. Semaphore array parameters should also be changed for DB2 to run successfully. To check shared memory segments, semaphore array, and message queue limits, issue the ipcs -l command.

From here, modify the kernel parameters by adding the following entries to the /etc/sysctl.conf default system control configuration file:

kernel.msgmni =512
kernel.sem =250 128000 32 1024

where:

max semaphores system wide = max number of arrays x max semaphores per array.

Now run the sysctl command with the -p parameter to load in sysctl settings from the default /etc/sysctl.conf file as follows:

sysctl -p

The entries from the sysctl.conf file are read during startup by the network initialization script.

On some distributions, you may be required to add sysctl -p in one of the system initialization files (for example, rc.local ) so that the kernel parameters are set after each reboot.

Two Web sites that you should be aware of for all your DB2 and Linux installation and compatibility needs are the DB2 for Linux How To site at http://www.tldp.org/HOWTO/DB2-HOWTO/kernel24.html and the DB2 for Linux Validation site at: http://www.ibm.com/software/data/db2/linux/validate .

2. Package names for SQL procedures are system generated and can't be changed by the user. This restriction is in place because DB2 needs to keep full control over these file names in order to properly handle libraries that have been loaded by the operating system and may subsequently become locked. In this case, if a rollback occurred, DB2 would need to generate a new name.

See a complete archive of reader/author Q&As .