10 Replies Latest reply: Feb 11, 2013 9:46 PM by yxes2013 RSS

    Dataguard Vs Standby

    yxes2013
      Hi All,

      I know most of you have experienced in production implem of standby and dataguard. For me I only done it on test theory and not yet on production becuase
      it generats lots of logs and also affects performance.
      Also For me I only do shutdown and copy the files to another disk since we can afford to shutdown the database after office hours.
      I have not considered that the database can crash anytime of the day and I will lose transactions of the day.
      But how do you protect your database which is in archivelog mode when the disk itelf where the logs resides get crashed and gets irrecoverable.
      And the even the reduntant copy of redo are also located on the same raid disk?

      What did you do when sometimes it happens the one of the archivelogs is missing or has 0 bytes size (meaning got corrupted)?

      Thanks a lot,

      Yxz
        • 1. Re: Dataguard Vs Standby
          sb92075
          yxes2013 wrote:
          Hi All,

          I know most of you have experienced in production implem of standby and dataguard. For me I only done it on test theory and not yet on production becuase
          it generats lots of logs and also affects performance.
          WRONG!
          only DML generates REDO
          • 2. Re: Dataguard Vs Standby
            yxes2013
            Ok... reasons accepted. :)
            • 3. Re: Dataguard Vs Standby
              sb92075
              DataGaurd is Oracle's implementation of a standby database.

              For non-Enterprise Edition Oracle DBs you can implement your own standby DB via minor OS scripting.
              Dataguard Vs Standby
              is like below

              Ford Vs Car
              • 4. Re: Dataguard Vs Standby
                970966
                Hi sb92075,

                You are right about that "*DML generates REDO*" but "only" not correct. Because If "*DELAYED BLOCKS CLEANOUTS*" have in your DB that REDO will produce with "SELECT". If you want, you can check "http://coskan.wordpress.com/2010/05/27/flashback-log-generation-with-select-statements/".

                If I've any mistake about that , please inform me...

                Regards..

                Thanks..
                • 5. Re: Dataguard Vs Standby
                  user639304
                  Hi sb92075,

                  I would add that you can check Oracle Core of Jonathan Lewis, or Oracle Database Architecture of Tiom Kyte to see that select can sometimes(Delayed Block Cleanout) generates redo.
                  • 6. Re: Dataguard Vs Standby
                    970966
                    Yes, It is correct.....
                    • 7. Re: Dataguard Vs Standby
                      Mihael
                      I know most of you have experienced in production implem of standby and dataguard. For me I only done it on test theory and not yet on production becuase
                      it generats lots of logs and also affects performance.
                      You are using noarchivelog mode on production database ? Once I have seen how after power failure and database restart, crash recovery was using some of archivelogs. But theoretically crash recovery does not require archivelog mode.
                      • 8. Re: Dataguard Vs Standby
                        yxes2013
                        Hi all,

                        I can only afford to setup standby as I do not have money to buy dataguard :(

                        Please can you enlighten me how can I recover my standby if my source database crashed and not recoverable anymore, like theres a bomb explode in my prod server while production is going on.
                        So there have been archive logs which lately committed and are current that is not yet transferred to the standby site. And I wonder how dataguard be able to address this?


                        Thanks a lot,
                        • 9. Re: Dataguard Vs Standby
                          mseberg
                          Hello;

                          If you are using Standard Edition you can setup a poor man's Data Guard. There's a very good note on it here :

                          http://managingoracle.blogspot.com/2012/04/oracle-manual-standby-no-dataguard.html

                          You can switch the TNSNAMES if the primary does crash as one option.

                          If you are really not using archivelog mode you should fix this ASAP.

                          Best Regards

                          mseberg
                          • 10. Re: Dataguard Vs Standby
                            yxes2013
                            Thanks dear :)