3 Replies Latest reply on Apr 17, 2020 9:04 AM by Beauty_and_dBest

    EBS 12.2 Dataguard

    Beauty_and_dBest

      EBS 12.2

      11gR2

      OL6

       

       

      Hi ALL,

       

      We have active dataguard setup  using > ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;

      I understand the above command is the only distinction between active not none-active dataguard right?

       

      I tried to create an table on primary database, and in split second the table is also created at the standby database.

      This happened even if there is no logfile switch and the archve log in not yet in transport.

       

      My Question is .....Does this mean that, when real life disaster and database failure happens,  I do not have data loss even if logs are not transported?

       

       

      Please help understand the dataguard process.

       

       

      Kind regards,

      jc

        • 1. Re: EBS 12.2 Dataguard
          Phill W.

          > "ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;"

           

          This command is the same for both Active and regular Data Guard.  Other things control whether the Standby is readable or not (can't tell you which, though, because my organisation hasn't licenced A.D.G.!).

           

          Yes, changes are replicated to the standby even before the archived redo log file is shipped to the standby server.

          This is controlled by one or more archive_log_dest_* variables being configured to "know about" the standby database service (and, course, when the database fails over, the new primary will know about the old one).  These are the additional [service]_DGB services [statically] registered with the Listeners.

           

          Regards,
             Phill  W.

          1 person found this helpful
          • 2. Re: EBS 12.2 Dataguard
            yoonas

            This happened even if there is no logfile switch and the archve log in not yet in transport.

            Data is not transported at the time of log switch it is done using Redo Transport Services

             

            My Question is .....Does this mean that, when real life disaster and database failure happens,  I do not have data loss even if logs are not transported?

             

            Log does not mean archived logs, it means redo logs which is transported using above given method based on your configuration for protection mode

            Oracle Data Guard Protection Modes

            For example in maximum protection mode, please refer above link to find more about all modes

             

            Maximum Protection

             

            This protection mode ensures that no data loss occurs if the primary database fails. To provide this level of protection, the redo data needed to recover a transaction must be written to both the online redo log and to the standby redo log on at least one synchronized standby database before the transaction commits. To ensure that data loss cannot occur, the primary database shuts down, rather than continue processing transactions, if it cannot write its redo stream to at least one synchronized standby database.

            All three protection modes require that specific redo transport options be used to send redo data to at least one standby database.

            1 person found this helpful
            • 3. Re: EBS 12.2 Dataguard
              Beauty_and_dBest

              Thanks Phill and yoonas,

               

              Supposing we encounter disaster, as in the source server got fire and burned down.

              We do not know much data was lost.

              But during our test, data is transferred in split second.

              Can we assume that we have minimal data loss?

              Or how to we account how much data was lost?

               

              Kind regards,