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RE: Paging problem

From: Kurth, Michael J. <>
Date: Tue, 27 May 2003 06:29:42 -0800
Message-ID: <>

You may also want to limit the amount of memory for the Unix buffer cache. I forget the parameter, but typically you would set this to around 25 - 30 %.
If you leave it to its default value, unix will hog much memory for the ubc. It also depends on if you are using raw devices or not.

-----Original Message-----
Sent: Monday, May 26, 2003 2:12 AM
To: Multiple recipients of list ORACLE-L

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 there anything needs to be done on OS level like setting the shared memory and semaphores as we do in case of SCO Unix.  


Arvind Kumar        

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Author: Kurth, Michael J.

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