10 Replies Latest reply: Mar 12, 2013 1:53 PM by Uwehesse-Oracle RSS

    Protection Mode

    995615
      Hello,

      I am new to data guard and only recently setup my first implementation of a primary and standby Oracle 11 g database.

      A) Correct me if i am wrong

      Flow of the No Real-time process:

      1) primary database sends redo data through redo transport process,
      2) the redo data is written to standby redo log;
      3) archive process archives the standby redo when there is a log switch;
      4) redo apply process applies the redo data to the standby.

      Am i right?

      B)My Database is in Maximum Performance mode. Without SRL at the standby site, is LGWR transport (LGWR ASYNC) possible?

      C) Is there any relationship between Log Transport mode and Data protection mode?

      With Regards
        • 1. Re: Protection Mode
          CKPT
          A) Correct me if i am wrong

          Flow of the No Real-time process:

          1) primary database sends redo data through redo transport process,
          2) the redo data is written to standby redo log;
          3) archive process archives the standby redo when there is a log switch;
          4) redo apply process applies the redo data to the standby.

          Am i right?
          Data Guard process LNS will be reading from redo buffer of SGA and passes redo to Oracle Net Services for transmission to the standby system, It writes in standby redo log files, according to the communication with primary data, archiving on standby will takes place.
          database.
          B)My Database is in Maximum Performance mode. Without SRL at the standby site, is LGWR transport (LGWR ASYNC) possible?
          You must configure Standby redo log files, if you want to use redo transport service LGWR
          C) Is there any relationship between Log Transport mode and Data protection mode?
          Data protection modes are different Like 1) maximum performance 2) maximum protection 3) maximum avaialbility
          Transport modes am not clear the question, as i understood correctly, whether it is archive data(ARCH) transport or LGWR.

          HTH.
          • 2. Re: Protection Mode
            Jos van den Oord
            Hi,
            Yes there is dependencies between redolog shipping and protection mode
            see [Table 5-1 Required Redo Transport Attributes for Data Protection Modes|http://docs.oracle.com/cd/B28359_01/server.111/b28294/protection.htm#CHDDAHJD]

            Cheers,

            Jos van den Oord
            Blog : [Joords Oracle DBA blog|http://joordsblog.vandenoord.eu/]
            Company : [Transfer-solutions.com|http://www.transfer-solutions.com/]
            • 3. Re: Protection Mode
              vlethakula
              A) If you want real time apply on stand by site, MRP (redo apply process) reads the changes from SRL(standby redo logs) and apply the changes.
              Instead of waiting them to be to be archived

              B)LGWR ASYNC requires SRL

              c)

              Performance Mode RedoTransport
              ------------------------ --------------------
              Max perf ARCH,LGWR ASYNC
              Max protection LGWR SYNC
              Max Availability LGWR SYNC
              • 4. Re: Protection Mode
                Uwehesse-Oracle
                You should always have Standby Logs (on both sides), regardless of the protection mode.
                SYNC and ASYNC transport mode is impossible without them.
                Especially, in 11g the ARCH transport mode is deprecated.

                Kind regards
                Uwe Hesse

                "Don't believe it, test it!"
                http://uhesse.com
                • 5. Re: Protection Mode
                  CKPT
                  Especially, in 11g the ARCH transport mode is deprecated.
                  Uwe,

                  I have a doubt here, Lets suppose we have not mentioned either ARCH or LGWR in "LOG_ARCHIVE_DEST_n" and we do not have standby redo log files, Then still archives will send to standby system. So still ARCH transport will be active. Only if we have standby redo log files then only it will send redo data.
                  Let me know if my assumption is wrong.
                  • 6. Re: Protection Mode
                    Uwehesse-Oracle
                    It is true that ARCH transport must be used if no standby redo logfiles are present - but that is not how it is supposed to be.
                    Deprecated does not mean technically impossible.
                    You will see warning messages in the alert log then, though.

                    Kind regards
                    Uwe Hesse

                    "Don't believe it, test it!"
                    http://uhesse.com
                    • 7. Re: Protection Mode
                      CKPT
                      It is true that ARCH transport must be used if no standby redo logfiles are present - but that is not how it is supposed to be.
                      Deprecated does not mean technically impossible.
                      Yeah, if we are using when supposed not to do, then such kind of warnings/errors/information messages are expected :)
                      You will see warning messages in the alert log then, though.
                      I can remember something like "Media recovery not performing Real-time apply" may be ;)
                      • 8. Re: Protection Mode
                        Hemant K Chitale
                        Uwe,

                        If the distance from the Primary to the Standby is in the order of thousands of kilometres ; the latency is in the order of 80ms-100ms .... would you still use LGWR (ASYNC obviously, not SYNC) ?


                        Hemant K Chitale
                        • 9. Re: Protection Mode
                          CKPT
                          Hemant K Chitale wrote:
                          Uwe,

                          If the distance from the Primary to the Standby is in the order of thousands of kilometres ; the latency is in the order of 80ms-100ms .... would you still use LGWR (ASYNC obviously, not SYNC) ?


                          Hemant K Chitale
                          I know you are waiting for the answer from Uwe, but still i like to participate in your question :)

                          Yes In maximum performance, we set only ASYNC redo transport, (No confirmation/No acknowledgment)

                          SYNC will be applicable for Maximum availability and protection, if your concern was on latency then maximum protection is not suitable, Still we can do some tuning at network level by adjusting SDU/TDU sizes, but in Maximum protection highly recommended to have more than one standby database, so that redo can write successfully at least one destination so that production will continues. in such case any one destination should be near and another destination is acceptable[still not recommended :) ] because we cannot predict when and where can be the network issues in whole data guard configuration.
                          • 10. Re: Protection Mode
                            Uwehesse-Oracle
                            Hemant,

                            yes, even for the largest distances, ASYNC transport mode is suitable.

                            Kind regards
                            Uwe Hesse

                            "Don't believe it, test it!"
                            http://uhesse.com