Problem:

Compiling legacy code with Server Express and running on AIX 5.x can incur singificant performance degradation with respect to same code compiled on older Micro Focus products (Object Cobol Developer Suite) on AIX 4.x. This performance degradation occurs when the system is using a JFS file systems.

Resolution:

Version 5 of IBM's AIX operating system can benefit from application of certain tuning parameters to JFS file systems. The following are general recommendations from IBM. The effect upon a specifc system may vary. Additional tuning may be required.

AIX 5.1

vmtune -c 4

This tuning command will not be retained across a reboot. Therefore, a small shell scirpt with this command should be executed from /etc/inittab at boot time.

AIX 5.2 and 5.3

ioo -p -o numclust=4

The effect of this command will be retained across a system restart. Note that the second command line switch is -[letter o], not zero.