DB Block Buffers - Too Much ???

From: Deepak Sharma <sharmakdeep_at_yahoo.com>
Date: Wed, 21 Jun 2000 09:07:04 -0700 (PDT)
Message-Id: <10535.110016@fatcity.com>

Recently on one of our test systems the Buffer Cache Hit Ratio was showing 80%. I increased
db_block_buffers from 6000 to 16000, and the after that the hit ratio has dropped to 55%. It seemed strange to me that increasing db_block_buffers should actually decrease performance, until I read Oracle tuning tips from Richard Niemiec, where he mentions too much db_block_buffers is not good too, as it may lead to swapping. My question is how do you determine whether the buffers are too low or too high ?

SQL> select state, count(*) from x$bh group by state;

     STATE COUNT(*)
---------- ----------

         1      13047
         3       2953

Does state = '1' mean this memory is not being used and if so, should I decrease the buffers ?

• Deepak

  ---

Oracle DBA,
Minneapolis, MN
USA

---

Do You Yahoo!?
Send instant messages with Yahoo! Messenger. Received on Wed Jun 21 2000 - 11:07:04 CDT