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Thread: redo contention-Urgent

  1. #1
    Join Date
    Jul 2000

    redo contention-Urgent

    Folks, I have a serious problem in production machine- as it became too slow and I found out there is contention in LGWR.
    DataFile Name Result
    ---------------------------------------- ---------------
    redo log space requests 2,017
    It has to be around 0, so please advice me . My current log_buffer parameter in init.ora is 10MB and I have 5 redo log groups of 512 KB each.Oracle 9i rel2 on Windows.
    If I increase the logbuffer and rebounce db is it going to solve, wondering more than 10MB will actually benefit or not?

  2. #2
    Join Date
    Jul 2002
    Northampton, England
    10MB already sounds rather large to me, but then without any details on your database, how can I judge? So, can we see a 15 minute statspack report and possibly a session trace (set events with waits) so we can see what effect these redo log space requests are having? Thanks ever so.
    Assistance is Futile...

  3. #3
    Join Date
    Jun 2005

    Re: redo contention-Urgent

    Originally posted by portal
    My current log_buffer parameter in init.ora is 10MB and I have 5 redo log groups of 512 KB each
    Hi Portal,

    I agree with waitecj that the 10 MB log_buffer is very much (Logwriter starts writing in case of commit or if log_buffer is 1/3rd full or if log_buffer is 1 MB full)

    And the 15-minutes statspack report requested by witecj is VERY important!

    But are you sure that your redologs files are only 512 KB ??? - or did you mean 512 MB ?
    10 MB log_buffer with 512 kb redo log file size is crazy.

    (I used on my billing system redolog file size 1 GB (3 Groups, 2 members) and switched every 5 minutes during billing run)

    How often are your log switches / how much redo do you write per minute / per hour ?

    (The old rule was "about every 20 minutes")

    At each redo log switch there occures a checkpoint, therefore 512 kb redo log file size seems to be the problem.

    Good Luck,


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