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Re: Paging problem

From: Mladen Gogala <mgogala_at_adelphia.net>
Date: Mon, 26 May 2003 00:36:48 -0800
Message-ID: <F001.005A27F5.20030526003648@fatcity.com>


Let's be simplistic about this. First, type ps -el|grep -v oracle. That will give you list of all processes except those ran by user oracle. Look at the column SZ and see which one is the largest. Do you have JDK,X11, GNOME, CDE, X terminals, Domino server or any other hog on the system? Do you have top? Run top and press capital M. That will sort processes by their resident memory. See which one doesn't belong to oracle and see if it is paging, and if it is, what is it doing and do you really, really want it? If no processes other then oracle ones are devouring memory, do you have dedicated server connections or MTS? May be you should consider MTS? If not, look at the sort area size, hash area size, OPEN_CURSORS (I've always been suspicious when it comes to the applications that open a gazillion of cursors). How about kernel configuration? How many buffers do you have? (NBUFF and NINODE parameters, now obsolete in most Unixes, but 4.3 is a rather old version). How about STREAMS? Do you have a gazillion of unnecessary streams buffers? Do you have OpenGL installed? Any processes named something like Doom, Xtetris, Invaders, Pacman (well, Pacman and Snake are rather old ones, but who knows. I used to play them on a big VAX 6440. Boy did they perform well, especially if given real-time priorities.) or alike? Are you running Samba, Apache, WebSphere or anything of that nature? Do you have 25,000 processes named "httpd"?

On 2003.05.26 03:11 Arvind Kumar wrote:
> Hi All,
>
> am facing the paging/swaping problem on AIX 4.3 running the oracle
> 8.1.5.i have 2GB of physical Memory and the total SGA is
> as below -
> buffer cache-350M
> Shared pool - 200M
> Log buffer -10 M
> Sort area size - 2M
> Sort area reatined size - 1M
>
> Database cache Hit Ratio is - 94 to 96%
> Library cache Hit Ratio is - 96%
>
> the most waited event is db_file_scattered_read , due to this i increased
> the value of db_file_multiblock_read_count from 16 to 64.
>
> maximum concurrent users connected is 80, at pick time.if i run the vmstat
> command the PI and PO column is always 2 and 1.
> in TOP command it shows that total memory usages is same as the total
> virtual memory usgaes means if my total memory use is
> 800M then the virtual is also of 800M.
>
> i am not able to find out why the paging is ocurring resulting the slow
> response.is there anything needs to be done on OS level
> like setting the shared memory and semaphores as we do in case of SCO Unix.
>
> Thanks
>
>
> Arvind Kumar
>
>
>
>
>

-- 
Mladen Gogala
Oracle DBA
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Mladen Gogala
  INET: mgogala_at_adelphia.net

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Received on Mon May 26 2003 - 03:36:48 CDT

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