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2 Replies Latest reply: Jan 21, 2011 2:28 AM by AndersSandal RSS

How to Resize Redo log groups

791045 Newbie
Currently Being Moderated
Windows Server 2008 64 bits - Oracle 11g (11.02.0)

We have our first oracle database in implementation.
The go live is supposed to happen in March or April.
Our Oracle courses will start next week but because of performance I need to change the size of our redo log groups.
The users are just loading 2010 year data into the database, but the performance is terrible.
I'd like to know if it's possible to do that by using the Enterprise Manager.
I was able to change the tablespaces and their files, but I don't succeed with redo log groups.
I have 3 groups with 50 MB each one. I'd like to change them to 500 Mb each one.
When I try to edit the groups, it doesn't open the possibility of changing it.
Do I have to stop the database ? do I have to clean the group ? how can I change the size of them ?

  • 1. Re: How to Resize Redo log groups
    vmalepati Newbie
    Currently Being Moderated
    Do this:

    Alter system switch logfile; Or

    Alter system checkpoint global;

    When a group is inactive then drop the group and recreate it.


    Suppose say when you issue above command group 1 becomes inactive then

    alter database drop logfile group 1;

    then create with

    alter database
    add logfile group 2
    (log1, log2) size 150M;

    Repeat the same for other groups.
  • 2. Re: How to Resize Redo log groups
    AndersSandal Newbie
    Currently Being Moderated

    As vmalepati says, you cannot resize redo log groups.
    Create three new log groups, with the size you need.
    As the database cycles through the loggroups, you will be able to drop the old (smaller) ones.

    1) find the instance in OEM
    2) enter the "Server" tab
    3) under "Storage", press "Redo log groups"
    4) login the database with a strong user
    5) Use the "create like"
    6) Edit the size and any other things you need, and press "ok"
    7) repeat 5 & 6 until you have the number of new redo log groups you need
    8) delete the old redologs. Pick the ones showing "Inactive"

    To force a logswitch, log in sqlplus as a strong user (system, for example)and execute the command
    alter system switch logfile;

    Best regards


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