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  1. #1
    Join Date
    Oct 2004
    Posts
    31

    Unanswered: How to calculate Oracle Redo rate ?

    Can someone explain how would I be able to calculate the Redo rate for using in the "Required bandwidth Formula" as seen below :



    Required bandwidth Formula
    Code:
    ((Redo rate in bytes per second / 0.7) * 8) / 1,000,000 = bandwidth in Mbps
    
    Example: 385 KB/sec peak rate would require an available network bandwidth of at least 
    
    ((394253 / 0.7) * 8) / 1,000,000 = 4.5 Mbps.

    I'm using Oracle 10g

  2. #2
    Join Date
    Nov 2006
    Location
    Indianapolis
    Posts
    90
    You're doing dataguard then?

    look at archive logs to find your busiest times and trends
    run statspack for 5 to 15 mins during those times to capture redo/sec averages
    or AWR should provide same info I would think...

  3. #3
    Join Date
    Oct 2004
    Posts
    31
    How about this ?



    Code:
    set serveroutput on
    declare
    lv_redo_start number;
    lv_redo_end number;
    begin
    select value into lv_redo_start from v$sysstat where name='redo size';
    select value into lv_redo_end from v$sysstat where name='redo size';
    dbms_output.put_line('Redo per second: ' || (lv_redo_end - lv_redo_start) / 5);
    end;

    When I run it though it jus hangs there....not doing anything

  4. #4
    Join Date
    Nov 2006
    Location
    Indianapolis
    Posts
    90
    Try adding a slash / at the end to execute the sql... in SQLPlus (and not some other tool)

    but I don't know what that SQL would show - getting redo size twice would be zero... perhaps you should do a dbms_lock.sleep(5) call in between.

    (that's essentially all statspack does - grabs v$ stats at snap1, grabs them later at snap2 and then reports on the deltas)

    v$sysstat shows values since instance startup. You want to catch a sample from the worst case, i.e. busiest database time...

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