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AIX High Swap usage

Posted on 2013-06-03
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Last Modified: 2013-07-30
Hi,

I am getting high swap usage on one of our AIX server every now and then. How can I check what all processes are consuming high swap on the system. I am seeing the NMON but I am not able to figure out which column show the swap usage. Can anybody explain how can we check that? This is urgent.

In topas it is showing PgSp column, whether that is the column which shows the processes using high Swap? How can I analyse the swap usage using any other tool on AIX?

Thanks
Virgo
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Question by:virgo0880
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woolmilkporc earned 1200 total points
ID: 39218268
nmon -> t -> 4

or:

export NMON=t4; nmon

shows process sizes and paging activity. Size (KB) is in the third column, paging I/O is in the 9th column.
Size means the total footprint of a process, i .e. memory (Res Set) + swap.

Get a quick overview of memory configuration/usage/paging under nmon by hitting "m", or by running "svmon -G" from the command line.

topas shows the total footprint of a process ( MB ) in the process section of the main panel under "PgSp", and, after hitting "P" (uppercase "P") in the process list under PAGE SPACE (in 4k pages!), You can sort by this column by positioning the cursor on it using the arrow keys.

Please note particularly for "topas" that other than "PAGING SPACE" and "PgSp" "TEXT RES" includes the executable program and shared libraries, so "TEXT RES"  might show a higher value than "PAGING SPACE".

Paging activity can be seen in the MEMORY/PAGING section of the main panel.

Finally,

svmon -P process_id

shows fine grain detail about memory and paging usage of a single process.
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Author Comment

by:virgo0880
ID: 39220823
I will verify this and revert back if there are any questions. Thanks.
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Author Comment

by:virgo0880
ID: 39227161
svmon -G
                          size       inuse        free         pin     virtual
memory      5767168     5171146      596022      747283     3876417
pg space    2883584      279586

                    work        pers        clnt       other
pin              536267           0           0      211016
in use          3784846     1091818      294482

The output of svmon is quite confusing. Can you explain the above output? and also what do you mean by section "pin in use" whether that is reserved for the processes?
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by:woolmilkporc
ID: 39227319
All values are in 4K pages!

size = Total size of memory ~ 22 GB
inuse = Pages in use by a process plus persistent (file) pages from terminated processes ~ 19.7 GB
free = Pages on the free list (= size minus inuse) ~ 2.3 GB
pin = pinned (non-pageable, always resident) pages (subset of "inuse) ~ 2.9 GB

"pg space" is your paging space in 4K pages (~11 GB),
"in use" (see below) is its used portion (~ 1.1 GB).

Don't get confused by "Virtual" being smaller than "memory inuse" + "pg space inuse"!
On AIX, pages in paging space may not be released when they are read back -
to maybe save the effort of having to page them out again.

"pin" and "in use" (lower part) = Breakdown of where pinned and "inuse" pages are used for.

work - working pages
pers - persistent (file) pages
clnt - client pages (remote file pages, NFS)
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Author Comment

by:virgo0880
ID: 39227378
That was a good explanation. I am digging more into this now to figure out the swap usage on my server. More to come.

Thanks
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