LinuxQuestions.org - [SOLVED] AIX using 90% of memory

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AIX using 90% of memory

Hi All, i have an AIX box running AIX 6.1 TL7 and only runs WebSphere and IHS, i noticed that the server was so slow, i contacted AIX team and they told me that this values are ok, it doesn't metter that % of memory used is above 90% whereas PageSpace is low, is that right?

Code:

          Physical  PageSpace

% Used    98.3%      0.2%

% Free      1.7%      99.8%

MB Used  4027.5MB    14.4MB

MB Free    68.5MB  8177.6MB

Does AIX have a "free" command like the one on Linux? Or another way of showing used memory not including buffers and cache?

There's no problem with having all your RAM used up with buffers and cache. What matters for performance is how much swapping is taking place, which would be affected by memory usage excluding buffers and cache.

What is the load average? uptime or tload will show you this - again, not sure if these exact commands are available on AIX. If load average is high, that means too many CPU tasks are queueing.

Hi there,

AIX generally uses all memory not needed for computational work, for filesystem cache, which means you'll typically see all memory used, and that is not a bad thing. Paging is the thing to look for most as your AIX team mentioned.

You can see how much memory is used for computational work vs filesystem cache in at least 2 ways.

If you have root access, run:

Code:

svmon -G -O unit=auto

You should see something like this:

Code:

Unit: auto

--------------------------------------------------------------------------------------

              size      inuse        free        pin    virtual  available  mmode

memory        8.00G      7.90G    106.04M      2.33G      3.49G      4.37G    Ded

pg space      8.00G    280.08M



              work        pers        clnt      other

pin          2.06G          0K        24K    273.00M

in use        3.30G      50.2M      4.55G

The "in use" line shows what is used, while the "work" column represents computational memory and the "clnt" (client pages) represents filesystem cache.

Without root access you should be able to see this on topas. To the right of the screen you will see something like this:

Code:

MEMORY

Real,MB    8192

% Comp    41

% Noncomp  56

% Client  56



PAGING SPACE

Size,MB    8192

% Used      3

% Free    97

I hope this helps.