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From: "David Sisk" <davesisk@ipass.net>
Newsgroups: comp.databases.oracle.server
References: <7lsvlv$j0$1@toto.tig.com.au>
Subject: Re: Online redo log tuning
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Date: Wed, 7 Jul 1999 23:05:58 -0400
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Dave:

These are all excellent questions.  See the Performance Tuning section of my
web-site.  (It's specific to NT, but all the rules and queries are the same
for any platform).  I think you'll find most of the answers there.....

Good luck,

--
David C. Sisk
The Unofficial ORACLE on NT site
http://www.ipass.net/~davesisk/oont.htm


Dave Waterworth wrote in message <7lsvlv$j0$1@toto.tig.com.au>...
>Hi,
>
>I'm currently tuning a database that is to be used as a emergency backup if
>a main server fails. It's running on a 256Meg server with only one disk.
>I've got a few question re the online redo logs and how there config
affects
>tuning.
>
>One session periodically loads a large amount of data into the system
>(deleting 50000 records, then replacing with 50000 new records, over about
>10 tables). I need to make sure this transaction doesn't peg the system
>(there are only a couple of other sessions active but they may be querying
>the same tables that are being deleted.
>
>I've set up the SGA to be 100Meg with 30Meg Redo Buffer which gives me
>pretty acceptible performance but the disk is still very busy during the
>insert. Using diskmon I see that the online redo logs are the culprits, I
do
>not care about recovert at all.
>
>1. I don't need to archive the redo logs, will increasing there size and
>hence reduce the frequency of log switches have much effect on performance
>or are log switches fairly cheap?
>
>2. With only 2 1M redo log files, is there a chance that the check pointing
>of log 1 is still in process when log is full, or is the check point
process
>pretty quick? Does checkpointing block a log switch? Does it matter if a
>single transaction fills all of the online logs then starts to overwrite
the
>initial file again?
>
>3. The log_checkpoint_interval is set to 10000 which I thinks means that
I'm
>checkpointing far more frequenctly than necessary. How do I disable this,
do
>I delete the entry in init.ora, set it to zero or a larger value?
>
>4. What exactly does the message checkpoint not complete mean and how do I
>eliminate it
>
>5. I notice that the starter database has two redo log groups, I assume
that
>both are being written too simultaneously which makes no sense on a single
>CPU single disk machine.
>
>Thanks in advance
>
>Dave Waterworth
>
>