RE: db_file_multiblock_read

From: Koivu, Lisa <lisa.koivu_at_efairfield.com>
Date: Mon, 25 Jun 2001 07:00:02 -0700
Message-ID: <F001.00336508.20010625062311@fatcity.com>

Hi Liam,

1. Setting db_file_multiblock_count to a number that when multiplied by your block size is greater than your max i/o size on your host will encourage full table scans. I also read somewhere else about the effects of doing this, I know there's more to it than what I've stated, but I don't remember off the top of my head (pre-coffee and post-run this am)

2. vmstat - look at the two columns that start with pg. Read the man page and it will explain it to you in detail. Also, when you use vmstat be sure to give it an interval (like vmstat 2 10 - this means display stats once every 2 seconds for a duration of 10 seconds). The first line returned by vmstat will always be garbage (same with iostat).

HTH
Lisa Koivu
Petite Clumsy Ninja-ette
Ft. Lauderdale, FL, USA

-----Original Message-----

From:   Liam Morrin [SMTP:dba37_at_hotmail.com]
Sent:   Monday, June 25, 2001 8:36 AM
To:     Multiple recipients of list ORACLE-L

Subject: db_file_multiblock_read_count

Listers,

I am attempting to tune a 7.3.4 OLTP database and I have a couple of questions.

The db_file_multiblock_count is 64 which seems way too high to me. What are the consequences, if any, of setting this parameter too high?
I want to increase the SGA to be 20% of the available memory (currently about 10%). Once I've made the change how can I tell if the Unix machine is paging memory without a fancy GUI tool?

Many thanks in advance,
Liam

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Author: Liam Morrin
INET: dba37_at_hotmail.com

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RE: db_file_multiblock_read_count