Quote:
Originally Posted by
learnbash
Actually my main concern is why buffer is 21gb
I will try to put it simple, so the experts might see some detail missing in order to make it easier to understand.
It so, because you told the system (see the values of "maxperm%" and "minperm%" in the output of
vmo -F -a) to preserve a certain amount of memory as free. The rest is first used for programs. When all the programs are loaded and there is still some of this memory available then this will be assigned to caching I/O-operations (this is your "buffer memory"). This assignment is temporary in nature and as soon as there is a program to be started an according amount of memory will be taken away from this buffer memory and given to the program. If some program ends, on the other hand, its memory will not be simply "free" (which means unused), but given to the buffer memory as long as it isn't needed elsewhere.
If you want to reduce buffer memory (which will probably have no adverse effects as far as i can tell) decrease the size of the assigned memory of the LPAR on the HMC profile. This will reduce the size of available memory after fulfilling all the programs requests and therefore less memory will be assigned to I/O-buffers.
Also investigate - together with the DBA! - the possibility of enlarging the SGA. To be honest i wonder how you get away with this much free memory without having the DBA pestering you to get it. In my experience they are a memory-hogging lot.
Btw., as i said before, the system is probably overpowered with respect to the physical CPUs assigned to it too. You might want to investigate possibilities to shrink that back to a sensible amount.
I hope this helps.
bakunin