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From: Ron Reidy <ron@indra.com>
Newsgroups: comp.databases.oracle.misc
Subject: Re: Redo Log maintenance
Date: Wed, 10 Oct 2001 20:33:16 -0600
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Wade Chy wrote:
> 
> Hi All
> I am helping somebody maintain the redo log. The database has 2 redo
> log files 1 mb each. They are filling up quick. I have to create 2
> more. If I just create 2 more log files, will it work or I have to
> create the rollback tablespaces and segments for it?
> The reason I am confused about it is because I tried to create a
> database with GUI Oracle Database Configuration Assistant. I saved the
> scripts for creating the database later. It saved 1 batch file and 4
> sql scripts. The first script creates the database with 2 log files
> sized 1024 k with the following statements:
> 
> CREATE DATABASE app
> LOGFILE 'E:\test_data\app\redo\redo01.log' SIZE 1024K,
>     'E:\test_data\app\redo\redo02.log' SIZE 1024K
> MAXLOGFILES 32
> MAXLOGMEMBERS 2
> MAXLOGHISTORY 1
> DATAFILE 'E:\test_data\app\system01.dbf' SIZE 10M REUSE
> MAXDATAFILES 254
> MAXINSTANCES 1
> CHARACTER SET WE8ISO8859P1
> NATIONAL CHARACTER SET WE8ISO8859P1;
> 
> And the the 2nd script that creates the tablespaces has the following
> statements:
> 
> REM ********** TABLESPACE FOR ROLLBACK **********
> CREATE TABLESPACE RBS DATAFILE 'E:\test_data\app\rbs01.dbf' SIZE 12M
> REUSE
> DEFAULT STORAGE ( INITIAL 1024K NEXT 1024K MINEXTENTS 2 MAXEXTENTS 121
> PCTINCREASE 0);
> ALTER DATABASE DATAFILE 'E:\test_data\app\rbs01.dbf' AUTOEXTEND ON;
> 
> CREATE PUBLIC ROLLBACK SEGMENT RB0 TABLESPACE RBS
> STORAGE (INITIAL 100K NEXT 250K);
> CREATE PUBLIC ROLLBACK SEGMENT RB1 TABLESPACE RBS
> STORAGE (INITIAL 100K NEXT 250K);
> ALTER ROLLBACK SEGMENT "RB0" ONLINE;
> ALTER ROLLBACK SEGMENT "RB1" ONLINE;
> 
> It creates a rollback tablespace and 2 rollback segments. What is the
> relation or difference between the log files and the rollback
> tablespce? Which one does the transactions use, the 'rbs01.dbf' or the
> 'E:\test_data\app\redo\redo01.log' SIZE 1024K,
> 'E:\test_data\app\redo\redo02.log' SIZE 1024K?
> Also is there any data dictionary view I can look at to find out if
> the redo log is filling out quickly and there are a lot of log
> switches. I am trying to find out if the smaller logfiles and low
> number of logfile is creating a performance problem.
> Please help.
> Thank you in advance.
Read the Oracle Admin docs.
-- 
Ron Reidy
Oracle DBA
Reidy Consulting, L.L.C.