ADSM-L

AIX memory tuning, needing some help !

2005-07-20 11:05:55
Subject: AIX memory tuning, needing some help !
From: PAC Brion Arnaud <Arnaud.Brion AT PANALPINA DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 20 Jul 2005 17:05:38 +0200
Hi gang,

I just moved my TSM server (5.3.1) to a brand new P550 (AIX 5.3), 8 GB
RAM : performance seems OK, but nmon and vmstat outputs are making me
feeling "uncomfortable" , in that they report very, very high page
faults ...
This is how it looks like :

vmstat 5

System configuration: lcpu=8 mem=7840MB

kthr    memory              page              faults        cpu    
----- ----------- ------------------------ ------------ -----------
 r  b   avm   fre  re  pi  po  fr   sr  cy  in   sy  cs us sy id wa
 2  0 860485 892282   0   0   0   0    0   0 429 202048 7586 56 24 20  0
 4  0 860306 892372   0   0   0   0    0   0 479 200803 7870 55 24 20  0
 4  0 860341 892520   0   0   0 104  565   0 541 203473 10387 56 24 19
1
 5  0 860204 892637   0   0   0  51  271   0 417 203636 8503 56 24 20  0
 4  0 860571 892118   0   0   0   0    0   0 404 202747 7691 56 24 20  0
 4  0 860362 892475   0   0   0  59  356   0 445 202569 8441 56 24 20  0
 2  0 860255 892429   0   0   0   0    0   0 393 201914 8035 56 24 20  0
 6  0 860528 892132   0   0   0   0    0   0 381 202421 7390 56 23 20  1
 5  0 860395 892417   0   0   0  60  375   0 382 202787 7686 56 23 20  0
 4  0 860217 892443   0   0   0   0    0   0 347 202069 7069 56 23 21  0
 3  0 860256 892512   0   0   0  51  280   0 347 203474 6887 56 23 20  0
 2  0 860437 892438   0   0   0  51  305   0 386 202040 7862 56 23 20  0
 3  0 860245 892478   0   0   0   0    0   0 371 202359 7320 56 24 20  0
 5  0 860520 892179   0   0   0   0    0   0 338 200080 6515 56 23 21  0
 4  0 860228 892447   0   0   0   0    0   0 345 203863 6916 56 24 20  0

As you can see, paging is mostly happening at "sy" level and does not
seem to affect performance : cpu wait = 0.

I have pretty limited knowledge of memory tuning, and was wondering what
this means, if it affects performance for my server, and if this can be
avoided using some improved vmo and/or ioo settings.

Actually I have this (largely inspired by my readings about memory
tuning in this list) :

vmo  -o maxperm%=40 -o strict_maxperm=1   -o maxfree=376  -o
maxclient%=20
ioo -o minpgahead=128 -o maxpgahead=256 -o numclust=1

Does this make sense to your eyes, or is there something I should modify
?
Thanks in advance for any explanations and/or advices !

Arnaud 

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