Check status of sync to standby

Question

Hi Guys
Whats the best way to check that your standby DB is in sync with the Primary ?
select current_scn from v$database;
Then compare the SCN numbers and ensure they are the same ?
Also archive logs need to be confirmed that they are being SHIPPED and APPLIED on standby ?
Is that enough to conclude that Standby is in sync ?
Thanks
Steve

Answer 1

Hi,
787789 wrote:
Whats the best way to check that your standby DB is in sync with the Primary ?
select current_scn from v$database;
Then compare the SCN numbers and ensure they are the same ?Get the RESETLOGS_CHANGE# from the primary database:
SQL> SELECT RESETLOGS_CHANGE#
FROM V$DATABASE_INCARNATION
WHERE STATUS = 'CURRENT';On the target physical standby database, identify any active standby redo logs (SRL’s)
SQL> SELECT GROUP#, THREAD#, SEQUENCE#
FROM V$STANDBY_LOG
WHERE STATUS = 'ACTIVE'
ORDER BY THREAD#,SEQUENCE#;On the target physical standby database, identify maximum applied sequence number(s).
SQL> SELECT THREAD#, MAX(SEQUENCE#)
FROM V$LOG_HISTORY
WHERE RESETLOGS_CHANGE#=< resetlogs_change# from the primary V$DATABASE_INCARNATION.RESETLOGS_CHANGE# >
GROUP BY THREAD#;The last SEQUENCE# for each THREAD# from V$LOG_HISTORY on the target physical standby database should be close (the difference in log sequences < 3) to the SEQUENCE# for each THREAD# from V$THREAD on the primary database.
Also archive logs need to be confirmed that they are being SHIPPED and APPLIED on standby ?
-- Verify that the primary has archived a log for the thread(s);
-- On the primary database issue the following;
SQL> SELECT THREAD#, MAX(SEQUENCE#)
FROM V$LOG_HISTORY
WHERE RESETLOGS_CHANGE# =
(SELECT RESETLOGS_CHANGE#
FROM V$DATABASE_INCARNATION
WHERE STATUS = 'CURRENT')
GROUP BY THREAD#;
-- Verify that the last sequence# received and the last sequence# applied to standby
-- database.
select al.thrd "Thread", almax "Last Seq Received", lhmax "Last Seq Applied"
from (select thread# thrd, max(sequence#) almax
      from v$archived_log
      where resetlogs_change#=(select resetlogs_change# from v$database)
      group by thread#) al,
     (select thread# thrd, max(sequence#) lhmax
      from v$log_history
      where first_time=(select max(first_time) from v$log_history)
      group by thread#) lh
where al.thrd = lh.thrd;>
Is that enough to conclude that Standby is in sync ?I recommend you use the Data Guard command-line interface (DGMGRL) to manage, and monitor a broker configuration.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14230/cli.htm
You can use this:
*Script to Collect Data Guard Physical Standby Diagnostic Information [ID 241438.1]*
*11.2 Data Guard Physical Standby Switchover Best Practices using SQL*Plus [ID 1304939.1]*
Monitoring Primary, Physical Standby, and Snapshot Standby Databases
http://download.oracle.com/docs/cd/E11882_01/server.112/e17022/manage_ps.htm#i1005610
Regards,
Levi Pereira