reduce paging

[sett2004]

Hi, I am running oracle 9.2 on a AIX 5.2 P650 server series.
server 8Gb memory, as my old server used to be, on my old server I used to have between 2 and 3% of paging space, that was configured using vmtune.
I tried to configure same parms on AIX 5L and I still having problems of paging 40% and 60% of top.
I have read that on oracle enviroments it is helpfull to reduce paging as much as you can, but I have not have success with vmtune or vmo.
any Idea?

 

[letis]

hello,

how do you monitor paging space ?
could you show us lines of the following commands when pagination occurs :

vmstat 1 (20 lines should be enough)
svmon -G

I assume that the paging spaces between the two systems have the same size of course )

last, how do you use vmtune/vmo on your new system ? command line or through smit ?

thanks,

 

[sett2004]

here you are
[SGCPRD] /prespaldos3/depuradores>vmstat 1
System Configuration: lcpu=4 mem=8192MB
kthr memory page faults cpu
----- ----------- ------------------------ ------------ -----------
r b avm fre re pi po fr sr cy in sy cs us sy id wa
10 2 1825682 260319 0 14 31 2637 50152 0 12892 54101 22870 37 15 32 17
4 6 1825686 260353 0 0 5 5958 127795 0 14226 48481 25694 36 14 21 29
3 3 1825686 260286 0 0 1 4995 65311 1 14130 58627 24227 40 9 14 36
2 3 1825686 260341 0 3 0 5525 70924 0 14117 48445 24653 35 11 11 43
4 2 1825686 260318 0 0 0 5880 83894 0 14161 48744 25705 33 14 22 32
13 2 1826734 259271 0 1 1 5875 80571 0 14084 54306 24432 36 15 18 32
1 4 1826734 259237 0 2 2 5003 44993 0 14195 48483 25325 31 9 16 44
2 3 1827125 258870 0 2 2 5766 71664 0 14168 54672 24193 36 13 14 37
3 3 1827141 258892 0 0 0 6428 118142 0 13941 48488 24181 33 10 24 33
1 3 1827141 258874 0 3 0 5046 84479 0 14097 48617 24614 30 12 22 36
1 4 1827141 258893 0 2 0 3771 74885 0 13861 48012 24923 32 16 20 32
2 3 1827141 258827 0 0 0 4574 56987 0 14097 48684 25787 33 11 10 46
3 2 1827158 258781 0 0 0 4083 68118 0 14173 49065 25318 36 13 14 37
1 3 1827158 258812 0 1 0 4937 69054 0 14203 48357 24531 32 12 26 30
1 3 1827158 258799 0 7 0 4211 42523 0 14130 48767 25144 34 8 12 45

svmon -G

[SGCPRD] /prespaldos3/depuradores>svmon -G
size inuse free pin virtual
memory 2097152 1843767 253385 229085 1830758
pg space 3145728 468220

work pers clnt lpage
pin 229286 0 0 0
in use 1640797 6855 196115 0

we use smit to be sure changes will be kept next boot.
at this time this number are showing our top this is because almost all our offices are closing.
we user topas to monitor % of paging growing up.

 

[letis]

re-hello,

what vmo settings (maxperm / minperm / maxclient) do you use ?
the svmon -G shows very few persistent pages compared to working pages , but you have many client pages compared to persistent ones (client are cdrom / nfs / jfs2 cached pages).


would you have installed you system in JFS2 instaad of the JFS that you had previousliy ? in this cas maxperm is not useful, maxclient is the parameter you must play with. Check with mount your filesystems type, can you confim us that you have jfs or jfs2 based fs ?

in the current sample, the paging space seems to be around 20% of use (quick estimation), what does lsps -a say ?


regards,

 

[Ogzilal]

Hi,

to know exactly what % of memory used for buffer files in your system, whitch is mybe the cause of your swapping, just type the following commands :

vmo -L minperm
The display will look like this
NAME CUR DEF BOOT MIN MAX UNIT TYPE
DEPENDENCIES
--------------------------------------------------------------------------------
minperm 200426 200426 S
--------------------------------------------------------------------------------

200426 is the minimum number of 4K pages reserved for buffer files in memory(about 10% of my 8388608 Kbyte memory )

To know the max % used for buffer files :

vmo -L maxperm

NAME CUR DEF BOOT MIN MAX UNIT TYPE
DEPENDENCIES
--------------------------------------------------------------------------------
maxperm 1565K 1565K S
--------------------------------------------------------------------------------

1565K is the max number of 4Kbyte pages reserved for buffer files.

Another important very parameter to know about is strict_maxperm :
vmo -L strict_maxperm

NAME CUR DEF BOOT MIN MAX UNIT TYPE
DEPENDENCIES
--------------------------------------------------------------------------------
strict_maxperm 1 0 1 0 1 boolean D
--------------------------------------------------------------------------------

Explanation : strict_maxperm is a boolean, when set to false (0), it tells the system to use more than maxperm parameter if needed, this way 100% of memory may be used for buffer files, leading to system crash in some situations.
when this parameter is set to true (1) maxperm % of memory will never be overpassed, buffer files in memory will be flushed out to disk evrytime they reach maxperm pages.

To change this parameters, commands will be like :

changing minperm : vmo -p -o minperm%=20
changing maxperm : vmo -p -o maxperm%=60
changing strict_maxperm : vmo -p -o strict_maxperm=1

minperm and maxperm are Static, the changes will take effect in next boot.

strict_maxperm is dynamic, the change takes effect immediatly.

man vmo for more deatails on other tunable parameters.

Ali