Max SCN Number in redolog file

Question

Hi ,
I have configured a data guard environment using below configuration
STANDBY TYPE : - PHYSICAL STANDBY
LOG TRANSPORT SERVICE : - ARCH [ ARCHIVE PROCESS ]
STANDBY LOG :- NO STANDBY LOG IN PRIMARY AND STANDBY
SYNC STATUS OF PRIMARY AND STANDBY : - FULLY SYNC
OPERATION  : - FAIL OVER USING 'ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;'
               ACTIVATING THE STANDBY USING ' ALTER DATABASE ACTIVATE STANDBY DATABASE;'
PRIMARY AND STANDBY ARE IN FULLY SYNC
ON PRIMARY
LAST ARCHIVED SEQUENCE NUMBER IS 12 AND FIRST AND LAST SCN ASSOCIATED WITH SEQUENCE 12 IS AS BELOW
SELECT SEQUENCE#,FIRST_CHANGE#,NEXT_CHANGE# FROM V$ARCHIVED_LOG WHERE SEQUENCE#=12;
SEQUENCE# FIRST_CHANGE# NEXT_CHANGE#
        12          669447                 670246
ON STANDBY
THE ARCHIVE LOG WITH SEQUENCE NUMBER 12 HAS ARCHIVED AND APPLIED ON STANDBY DATABASE SUCCESSFULLY.
NOW I AM DOING A FAIL OVER BY USING THE BELOW COMMANDS
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
ALTER DATABASE ACTIVATE STANDBY DATABASE;
ALERT  LOG ON STANDBY DATABASE
Media Recovery Log /data/PRD_DR/arch/arch_1_11_834360625.arch
Media Recovery Log /data/PRD_DR/arch/arch_1_12_834360625.arch
Media Recovery Waiting for thread 1 sequence 13
Error 12154 received logging on to the standby
FAL[client, MRP0]: Error 12154 connecting to PRD for fetching gap sequence
Errors in file /apps/oracle/diag/rdbms/stand/PRD/trace/PRD_mrp0_7865.trc:
ORA-12154: TNS:could not resolve the connect identifier specified
Thu Dec 26 18:00:36 2013
alter database recover managed standby database cancel
Thu Dec 26 18:00:36 2013
MRP0: Background Media Recovery cancelled with status 16037
Errors in file /apps/oracle/diag/rdbms/stand/PRD/trace/PRD_mrp0_7865.trc:
ORA-16037: user requested cancel of managed recovery operation
Shutting down recovery slaves due to error 16037
Recovery interrupted!
Errors in file /apps/oracle/diag/rdbms/stand/PRD/trace/PRD_mrp0_7865.trc:
ORA-16037: user requested cancel of managed recovery operation
MRP0: Background Media Recovery process shutdown (PRD)
Waiting for MRP0 pid 7865 to terminate
Managed Standby Recovery Canceled (PRD)
Completed: alter database recover managed standby database cancel
Thu Dec 26 18:00:59 2013
alter database activate standby database
ALTER DATABASE ACTIVATE [PHYSICAL] STANDBY DATABASE (PRD)
tkcrrxms: Killing 2 processes (all RFS)
RESETLOGS after incomplete recovery UNTIL CHANGE 670246
Resetting resetlogs activation ID 1898010833 (0x712158d1)
Online log /data/PRD_DR/REDOLOG11.LOG: Thread 1 Group 1 was previously cleared
Online log /data/PRD_DR/REDOLOG21.LOG: Thread 1 Group 2 was previously cleared
Online log /data/PRD_DR/REDOLOG33.LOG: Thread 1 Group 3 was previously cleared
Standby became primary SCN: 670244
Thu Dec 26 18:01:01 2013
Setting recovery target incarnation to 3
Converting standby mount to primary mount.
ACTIVATE STANDBY: Complete - Database mounted as primary (PRD)
Completed: alter database activate standby database
IN STANDBY ALERT LOG I CAN SEE BELOW THINGS
RESETLOGS after incomplete recovery UNTIL CHANGE 670246
Standby became primary SCN: 670244
MY QUESTION IS ON 'SCN NUMBER OF 'Standby became primary SCN: 670244'.
I HAVE CHECKED THE SCN NUMBERS OF THE ARCHIVE LOG OF SEQUENCE 12 [ USING LOGMINER ] THE MAX SCN ASSOCIATED WITH THE ARCHIVE LOG IS 670242
SELECT MAX(SCN) FROM V$LOGMNR_CONTENTS; [ FOR LOGMINER I HAVE USED '
EXECUTE DBMS_LOGMNR.START_LOGMNR(OPTIONS => DBMS_LOGMNR.DDL_DICT_TRACKING + DBMS_LOGMNR.DICT_FROM_REDO_LOGS); ]
  MAX(SCN)
  670242
- WHY IN LOGMINER MAX(SCN) IS NOT SHOWING AS 670246 ?
- HOW I CAN SEE THE SCN 670244 FOR ARCHIVE LOG FOR SEQUENCE NUMBER 12 ?
Thanks,

Answer 1

IN STANDBY ALERT LOG I CAN SEE BELOW THINGS
RESETLOGS after incomplete recovery UNTIL CHANGE 670246
Standby became primary SCN: 670244
MY QUESTION IS ON 'SCN NUMBER OF 'Standby became primary SCN: 670244'.
I HAVE CHECKED THE SCN NUMBERS OF THE ARCHIVE LOG OF SEQUENCE 12 [ USING LOGMINER ] THE MAX SCN ASSOCIATED WITH THE ARCHIVE LOG IS 670242
in fact, it is really intelligent question.
First you have to know the sequence 12, next_change# is not belongs to 12 but it belongs to the 13th sequence first_change...
So in the real, the seqeunce 12 change number is only up to 670245 and the change 670246 is the starting change of sequence numebr 13.
It is not using any real time apply, Now as per the my above conclusion the sequence number last change is only 670245 , As per the recovery concepts.. If you want to perform recovery change up to 100, you need to mention as "until 100 + 1", i.e. 101.. So if you mention 101 then it performs recovery until 100.
1) the 12 sequence max change is 670245
2) when it performs recovery until that sequence, then then usually it performs recovery until 6740244 as per the recovery rules.
From http://docs.oracle.com/cd/B19306_01/server.102/b14357/ch12033.htm
UNTIL CHANGE integer
Processes managed recovery up to but not including the specified system change number (SCN).
Still at this point am not giving conclusion 100%, am testing same as you using log miner and will let you know sure..
- WHY IN LOGMINER MAX(SCN) IS NOT SHOWING AS 670246 ?
When you analyze archive redo log file, Have you used starttime and end time? Note that if you give end time bit less then there is chance to truncate to gather information for log miner and important thing is Oracle writes checksum information and change information in terms of metadata into headers.Also note that oracle uses some of records for SYSTEM CHANGE, so some of them may not visible.
HTH.