How to find out the actual memory consumption of the server

The command svmon -G can be used to determine the actual memory consumption of a server. To determine if the memory is overcommitted, you need to divide the memory-virtual value by the memory-size value, e.g.:

# svmon -G

               size       inuse        free         pin     virtual

memory      5079040     5076409        2631      706856     2983249

pg space    7864320       12885

               work        pers        clnt       other

pin          540803           0        2758      163295

in use      2983249           0     2093160

PageSize   PoolSize      inuse       pgsp        pin    virtual

s   4 KB          -    4918761      12885     621096    2825601

m  64 KB          -       9853          0       5360       9853

In this example, the memory-virtual value is 2983249, and the memory-size value is 5079040. Note that the actual memory-inuse is nearly the same as the memory-size value. This is simply AIX caching as much as possible in its memory. Hence, the memory-free value is typically very low.

Now, to determine the actual memory consumption, devide memory-virtual by memory-size:

2982321/5079040

.58

Thus, the actual memory consumption is 58% of the memory.

Total memory = 19840 MB

Actual memeory consumption size:  58%*19840=11507 MB

The free memory is thus: (100% - 58% ) * 19840 MB = 8332 MB.

Try to keep the value of memory consumption less than 90%. Above that, you will generally start seeing paging activity using the vmstat command. By that time, it is a good idea to lower the load on the system or to get more memory in your system.