Why is the Process memory percentage zero?
This seems to happen in AIX 5.3 TL07 or there about. In fact, it is the AIX libperfstat library, which nmon uses, that has a bug in it that returns a large negative number for the Process% value. The Process, System and User Percentages are approximations (remember memory has many modes, types and uses and some overlap) and the calculation goes wrong. nmon reports this problem by showing 0% – which is clearly impossible. The bug was very hard to reproduce and track down because the problem only happens in particular circumstances and changes in memory use (like starting and stopping large memory applications). I am pretty sure you have a good chance of the number being fixed (for at least some time but may reappear), if you reboot the machine/LPAR. The fix is to update AIX to AIX 5.3 TL09 (or even better AIX 6) but there may be a PTF or efix. You will have to ask AIX Support by asking for a fix to the libperfstat library to fix the real_system, real_process and real_user members of the
