Re: Buffer cache hits %

From: Jiliang Chiu <lchiu_at_bellsouth.net>
Date: Thu, 15 Jul 1999 15:20:34 -0500
Message-ID: <Urqj3.7410$xK4.30626@news3.atl>

Kevin:

The hit ratio should be 95 - 100%.

You can use X$KCBRRH (raise buffer hits) and X$KCBCBH (crushes buffe hits) to check the statistics for adding or = removing buffers.
(connect as sys)

Run UTLBSTAT and UTLESTAT to get detials of your performance = information.
(connect as intenal will do)

Start databaase for sometime before you run UTLBSTAT, try to collect = whole session.

JC
Kevin Gillins <kevin_gillins_at_compuserve.com> wrote in message = news:O41ialrz#GA.309_at_nih2naae.prod2.compuserve.com... I have a question about the buffer cache hits ratio we are = experiencing.

  We are on 7.3.3.5 database using 10.7 oracle apps most all products. = Apx 100+ users.
  The database size is apx 40 gig. We are on HP 4 processors with 2.5 = gig memory.
  There are 2 instances both the same size (prod and test). The shared = pool is set
  at 250,000,000 running 6 db writers. The production instance is on = EMC disks.

My main question is the buffer cache hit% is sitting at 90% in = general. Is this good, bad or
real bad. I want to get a feel. I have tried increasing the shared = pool and db_block_buffers.

What other settings if any would improve this statistic. What stats = could I check to see
what contributes to the 10% miss?

Your suggestions and answers are appreciated.

  Kevin Gillins
  Management Information Consulting
  Boston Office
  978-887-3300     Received on Thu Jul 15 1999 - 15:20:34 CDT