Oracle Database Discussions

Hello sir ,
Me JR.DBA working at Production Site.Our system configuration is
OS :WINDOWS NT
ORACLE:9i
RAM :4GB
NO OF SESSIONS OPENING AT PEAK TIME :200
only ORACLE is running on the server.
I have allotated 50% of physical memory to ORACLE
that is in total 4GB 2GB alloted to ORACLE.
In morning time performance is fine but at peak time (from 10:30) that is when no of
sessions increased, server
performance is abruptly coming down.I have checked the hit ratios by using following

Buffer Cache;
SQL> select 1-(sum(decode(name,'physical reads',value,0))/
(sum(decode(name,'db block gets',value,0)) +
(sum(decode(name,'consistent gets',value,0))))) "Hit Ratio"
from v$sysstat;
SQL>99%

Shared Pool:
SQL>select (sum(pinhits)/sum(pins)) * 100 from v$librarycache
SQL>99.34%
the above ratios are fine.I also checked the LONGOPERATIONS and i have tuned them ,even though performace in not good,I am

not getting why server is becoming slow.
Can u please assist me on this ,what are the other problems that will affect the server
performance and what i need to check else.
Is it good to increase the RAM size and SGA size, because of no of sessions increased.


OUR BUFFER CACHE ADVICE
SQL>SELECT BLOCK_SIZE, SIZE_FOR_ESTIMATE ,SIZE_FACTOR, ESTD_PHYSICAL_READ_FACTOR, ESTD_PHYSICAL_READS from V$DB_CACHE_ADVICE

BLOCK_SIZE SIZE_FOR_ESTIMATE SIZE_FACTOR ESTD_PHYSICAL_READ_FACTOR ESTD_PHYSICAL_READS
---------- ----------------- ----------- ------------------------- -------------------
4096 64 .0952 16.3137 8078209378
4096 128 .1905 5.239 2594257605
4096 192 .2857 3.7891 1876307867
4096 256 .381 2.9744 1472862267
4096 320 .4762 2.4274 1201979642
4096 384 .5714 2.0237 1002073833
4096 448 .6667 1.7094 846476752
4096 512 .7619 1.453 719511999
4096 576 .8571 1.2471 617528972
4096 640 .9524 1.0754 532540477
4096 672 1 1 495179540(CURRENT SIZE)

BLOCK_SIZE SIZE_FOR_ESTIMATE SIZE_FACTOR ESTD_PHYSICAL_READ_FACTOR ESTD_PHYSICAL_READS
---------- ----------------- ----------- ------------------------- -------------------
4096 704 1.0476 .9303 460686207
4096 768 1.1429 .8072 399724181
4096 832 1.2381 .7053 349243366
4096 896 1.3333 .6196 306827584
4096 960 1.4286 .5469 270829139
4096 1024 1.5238 .4874 241359855
4096 1088 1.619 .4365 216133997
4096 1152 1.7143 .3899 193062888
4096 1216 1.8095 .3507 173674938
4096 1280 1.9048 .3144 155667423






SQL> select SHARED_POOL_SIZE_FOR_ESTIMATE,ESTD_LC_SIZE,ESTD_LC_TIME_SAVED_FACTOR,ESTD_LC_MEMORY_OBJECT_HITS from

V$shared_pool_Advice;

SHARED_POOL_SIZE_FOR_ESTIMATE ESTD_LC_SIZE ESTD_LC_TIME_SAVED_FACTOR ESTD_LC_MEMORY_OBJECT_HITS
----------------------------- ------------ ------------------------- --------------------------
344 330 .9966 48865819
408 393 .997 48901875
472 456 .9974 48952727
536 519 .9977 48998219
600 582 1 49038424(CURRENT)
664 645 1.0002 49072271
728 708 1.0004 49099218
792 771 1.0005 49123837
856 834 1.0007 49148519
920 897 1.0008 49171906
984 960 1.0009 49192687

SHARED_POOL_SIZE_FOR_ESTIMATE ESTD_LC_SIZE ESTD_LC_TIME_SAVED_FACTOR ESTD_LC_MEMORY_OBJECT_HITS
----------------------------- ------------ ------------------------- --------------------------
1048 1023 1.001 49211828
1112 1086 1.0011 49232725
1176 1149 1.0014 49268576
1240 1228 1.0016 49307910

Regards,
Vamsi