6 Replies Latest reply: Aug 21, 2009 6:04 AM by aram RSS

    physical standby and logical standby

    user3266490
      Hi,
      Why we mention standby_archive_dest and log_archive_Dest in standby init.ora.
      bcz there is no activity at physical standby.so why we set two parameters?


      what is difference between physical stand by and logical standby?
        • 1. Re: physical standby and logical standby
          Pavan DBA
          please read this doc which will clear all your doubts.
          http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/toc.htm
          • 2. Re: physical standby and logical standby
            669771
            Hi,

            A logical standby database contains the same logical information as the production database, although the physical organization and structure of the data can be different. The SQL apply technology keeps the logical standby database synchronized with the primary database by transforming redo data received from the primary database into SQL statements and then executing the SQL statements on the standby database. This makes it possible for the logical standby database to be open read-write and accessed for queries and reporting purposes at the same time the SQL is being applied to it.

            Logical vs Physical Standby database
            http://www.orafaq.com/node/957

            Regards,
            Tom

            Edited by: Soli on 19.8.2009 13:48
            • 3. Re: physical standby and logical standby
              Sanghai
              Hi,

              Physical standby database can only be open as read only and once it is switch to primary database it can never be switch to standby mode.
              Logical standby database can be opened in read and write mode.

              Thanks and Regard.
              • 4. Re: physical standby and logical standby
                546111
                Are you sure about your statement below.
                "once it is switch to primary database it can never be switch to standby mode."
                Can you please provide me the link from where you find the statement above
                Switch over and fail over applies only for logical standby databases?

                Edited by: SMH on Aug 21, 2009 3:36 AM
                • 5. Re: physical standby and logical standby
                  aram
                  Hai
                  i dont feel ur answer is correct bcoz switchover is common for both physical and logical stanby databases.

                  standby databases whether physical or logical is mainly designed for the purpose of performing switchover during production database backups.
                  • 6. Re: physical standby and logical standby
                    aram
                    U see standby_archive_dest parameter mentioned in the standy init file indicates the location in target standby database where the archive logs received from the primary database will be stored.

                    log_archive_dest parameter indicates the location in the standby where the standby archive logfiles will be stored.

                    sometimes the standby database will act as primary database during switchovers.At that time the manipulations performed by the users will lead to the generation of archive log files in standby database which is presently acting as the primary database.

                    that's the reason for mentioning these parameters in the standby init parameter file ...........