5 Replies Latest reply: Feb 9, 2014 1:17 AM by user591655 RSS

Physical standby

975791 Explorer
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Is it possible create physical standby without standby log in oracle 10g/11g?

If it's,how does recovery happen?





  • 1. Re: Physical standby
    Baris Yildirim Guru
    Currently Being Moderated


    yes it's possible


    When you use ARCH process on primary to transport archived logs, you doesn't have to use standby log file on standby.



  • 2. Re: Physical standby
    Baris Yildirim Guru
    Currently Being Moderated



    but you should find out that if you lose your primary (crash,disaster etc), you will lose all transactions in current redo log file.



  • 3. Re: Physical standby
    JohnWatson Guru
    Currently Being Moderated

    You can certainly run a standby database without standby logs. There is no change to the transmission of redo by the primary: this is done by LGWR LNS processes as usual. On the standby, the RFS process writes the redo to an archive logfile if no suitable standby logfile is available. The only problem is that real time apply cannot be used in this circumstance. You must wait for the archive logfile to be complete (ie, a log switch on the primary) before the MRP can apply the redo.

    There are many possibilities with Data Guard, I went through some of them in this recording:

    Oracle Data Guard Free Tutorial: Data Guard for Performance and Reduced Licensing Costs

  • 4. Re: Physical standby
    Alvaro Pro
    Currently Being Moderated

    It's worth noting, complementing Mr. Watson answer, that because of this, the dataguard will always be one sequence behind the primary.


    What this means is that for a failover, you will lose data generated since the last redo log switch.



  • 5. Re: Physical standby
    user591655 Journeyer
    Currently Being Moderated



    In case you do not have Standby Redo Logs, an Archived Redo Log is created

    by the RFS process and when it has completed, this Archived Redo Log is applied

    to the Standby Database by the MRP (Managed Recovery Process) or the Logical

    Apply in Oracle 10g when using Logical Standby. An open (not fully written)

    ArchiveLog file cannot be applied on the Standby Database and will not be used

    in a Failover situation. This causes a certain data loss.



    If you have Standby Redo Logs, the RFS process will write into the Standby Redo

    Log as mentioned above and when a log switch occurs, the Archiver Process of the

    Standby Database will archive this Standby Redo Log to an Archived Redo Log,

    while the MRP process applies the information to the Standby Database.  In a

    Failover situation, you will also have access to the information already

    written in the Standby Redo Logs, so the information will not be lost.




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