9 Replies Latest reply: Mar 9, 2013 8:51 AM by Mihael RSS

    Log_file_name_convert

    934234
      Hello,

      a)The Online Redo Log file doesn’t come in picture anywhere in the Physical Standby. Is there any need to set LOG_FILE_NAME_CONVERT parameter on the standby database?

      b) RFS process writes the redo data to either archived redo log files or standby redo log files. Will RFS Process writes the redo to SRL properly,If the size of the standby redo log files does not match the size of primary database online redo log files i.e SRL size is lesser than the ORL size?
        • 1. Re: Log_file_name_convert
          Mihael
          a)The Online Redo Log file doesn’t come in picture anywhere in the Physical Standby. Is there any need to set LOG_FILE_NAME_CONVERT parameter on the standby database?
          Yes, in case of switchover or failover to standby
          b) RFS process writes the redo data to either archived redo log files or standby redo log files. Will RFS Process writes the redo to SRL properly,If the size of the standby redo log files does not match the size of primary database online redo log files i.e SRL size is lesser than the ORL size?
          the size should be the same on primary and standby
          • 2. Re: Log_file_name_convert
            CKPT
            a)The Online Redo Log file doesn’t come in picture anywhere in the Physical Standby. Is there any need to set LOG_FILE_NAME_CONVERT parameter on the standby database?
            read below content from the link
            >
            LOG_FILE_NAME_CONVERT converts the filename of a new log file on the primary database to the filename of a log file on the standby database. If you add a log file to the primary database, you must add a corresponding file to the standby database.

            If you specify an odd number of strings (the last string has no corresponding replacement string), an error is signalled during startup. If the filename being converted matches more than one pattern in the pattern/replace string list, the first matched pattern takes effect. There is no limit on the number of pairs that you can specify in this parameter (other than the hard limit of the maximum length of multivalue parameters).

            When the standby database is updated, this parameter converts the log file name on the primary database to the log file name on the standby database. The file must exist on the standby database and must be writable or the recovery process will halt with an error.

            The first string is the pattern found in the log file names on the primary database. The second string is the pattern found in the log file names on the standby database.

            You should also use LOG_FILE_NAME_CONVERT to rename the logfiles in the clone control file when setting up the clone database during tablespace point-in-time recovery.
            >

            Source:
            http://docs.oracle.com/cd/B19306_01/server.102/b14237/initparams112.htm

            b) RFS process writes the redo data to either archived redo log files or standby redo log files. Will RFS Process writes the redo to SRL properly,If the size of the standby redo log files does not match the size of primary database online redo log files i.e SRL size is lesser than the ORL size?
            1) You must have same size or more size than online redo log files
            2) you must have same number of standby redo log groups as online redo log files (or) more, If maximum protection, availability you must have extra one group.
            • 3. Re: Log_file_name_convert
              Mihael
              1) You must have same size or more size than online redo log files
              "The size of the current standby redo log files must exactly match the size of the current primary database online redo log files."

              from http://docs.oracle.com/cd/B19306_01/server.102/b14239/create_ps.htm#i1225703
              • 4. Re: Log_file_name_convert
                Seberg
                B14239-05 is a four and one half year old Oracle 10 document.

                If you check something more recent say Data Guard Concepts and Administration 11g Release 2 (11.2) E10700-02

                6.2.3 Configuring an Oracle Database to Receive Redo Data

                "Each standby redo log file must be at least as large as the largest redo log file in the redo log of the redo source database"
                • 5. Re: Log_file_name_convert
                  Mihael
                  Yes, I agree. For 11g it is only recommendation:
                  "For administrative ease, Oracle recommends that all redo log files in the redo log at the redo source database and the standby redo log at a redo transport destination be of the same size."
                  • 6. Re: Log_file_name_convert
                    CKPT
                    Mihael wrote:
                    Yes, I agree. For 11g it is only recommendation:
                    "For administrative ease, Oracle recommends that all redo log files in the redo log at the redo source database and the standby redo log at a redo transport destination be of the same size."
                    Michael,

                    Now what is the issue if Standby redo log files have more size than online redo log files? It can have higher size and can have higher number of redo groups.
                    It is wrong assumption, if the size should be same as Online redo log files.

                    can you prove me ?
                    • 7. Re: Log_file_name_convert
                      Mihael
                      Michael,

                      Now what is the issue if Standby redo log files have more size than online redo log files? It can have higher size and can have higher number of redo groups.
                      It is wrong assumption, if the size should be same as Online redo log files.

                      can you prove me ?
                      Yes, I have already mentioned, that it was from 10g docs.
                      But there is one question. If standby redo logs are bigger than primary online redo, then standby site will generate different archivelogs, with different size, sequence, first and last scn. If this is true, then, for example, how can we recover primary site with archivelogs from standby? Should we reregister them? Please, correct me if this is wrong.
                      • 8. Re: Log_file_name_convert
                        CKPT
                        Yes, I have already mentioned, that it was from 10g docs.
                        But there is one question. If standby redo logs are bigger than primary online redo, then standby site will generate different archivelogs, with different size, sequence, first and last scn.
                        Nope, if log switch occurred then immediately it will be forced on standby database also, You can compare the size of primary and standby archive log files.
                        You thinking as, even though log switch occurred on primary, still it continue writing in standby log file until it fulls.
                        If this is true, then, for example, how can we recover primary site with archivelogs from standby? Should we reregister them? Please, correct me if this is wrong.
                        Hope, you have answer already from the above point, Standby is an identical copy of primary.
                        • 9. Re: Log_file_name_convert
                          Mihael
                          Nope, if log switch occurred then immediately it will be forced on standby database also, You can compare the size of primary and standby archive log files.
                          You thinking as, even though log switch occurred on primary, still it continue writing in standby log file until it fulls.
                          If this is true, then, for example, how can we recover primary site with archivelogs from standby? Should we reregister them? Please, correct me if this is wrong.
                          Hope, you have answer already from the above point, Standby is an identical copy of primary.
                          Thank you!