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How does SGA and PGA split memory when we use MEMORY_TARGET [message #449254]

Sun, 28 March 2010 22:43

shrinika
Messages: 306
Registered: April 2008

Senior Member

Hello,

I read in few blog and they are saying, oracle11g allocate
60% of the memory to SGA and 40% of the memory to PGA
when we enable MEMORY_TARGET to non-zero.

Here are few blogs...

http://hemora.blogspot.com/2009/12/memory-parameters-in-11g-memorytarget.html

http://oracle-online-help.blogspot.com/2008/03/memory-parameters-in-11g-memorytarget.html

http://opsc.itpub.net/post/38822/497514

http://asanga-pradeep.blogspot.com/2009/10/memory-target-on-11g.html

It is not working on that way(60:40) on my database.

Here is my DB version.

Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
PL/SQL Release 11.1.0.7.0 - Production
CORE    11.1.0.7.0      Production
TNS for Linux: Version 11.1.0.7.0 - Production
NLSRTL Version 11.1.0.7.0 - Production

Here memory_target is 11GB. SGA is not showing 60%
of memory_target....

SQL> select value from v$parameter where name='memory_target';

VALUE
--------------------------------------------------------------------------------
11811160064

SQL> show sga

Total System Global Area 1.2827E+10 bytes
Fixed Size                  2163968 bytes
Variable Size            6979324672 bytes
Database Buffers         5771362304 bytes
Redo Buffers               74518528 bytes
SQL> select (2163968+6979324672+5771362304+74518528)/1024/1024/1024
  2  from dual;

(2163968+6979324672+5771362304+74518528)/1024/1024/1024
-------------------------------------------------------
                                             11.9464188

SQL>

I am not able to find 60%:40% concept in oracle document...
so all the above blogs info are wrong?

Any clarification is helpful.

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Re: How does SGA and PGA split memory when we use MEMORY_TARGET [message #449255 is a reply to message #449254]

Sun, 28 March 2010 22:52

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

post results from SQL below

SELECT * FROM V$SGA_TARGET_ADVICE;

>I read in few blog and they are saying, oracle11g allocate 60% of the memory to SGA and 40% of the memory to PGA

What happens if you need to run more than 1 instance on a single system?

Not everything found on the 'Net is true.

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Re: How does SGA and PGA split memory when we use MEMORY_TARGET [message #449424 is a reply to message #449255]

Mon, 29 March 2010 08:49

shrinika
Messages: 306
Registered: April 2008

Senior Member

Here is the result...

SQL> select * from v$sga_target_advice;

  SGA_SIZE SGA_SIZE_FACTOR ESTD_DB_TIME ESTD_DB_TIME_FACTOR ESTD_PHYSICAL_READS
---------- --------------- ------------ ------------------- -------------------
       360               1          730                   1               22667
       180              .5         1501              2.0567               31804
       270             .75          784              1.0738               23440
       450            1.25          730                   1               22667
       540             1.5          724               .9915               22438
       630            1.75          724               .9915               22438
       720               2          724               .9915               22438

7 rows selected.

What happens if you need to run more than 1 instance on a single system?

In my system, i have only one instance. Not sure, how it works if there is more then one instance in single system...

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