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DataGuard
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Hi, everyone. We have used SELECT commands several times. Today I want to introduce some views and tables which help to manage Physical Standby.
To confirm Role Log Mode, Control File Type and Protection Mode
Refer to v$database to confirm current Role Log Mode, Control File Type and Protection Mode.
SQL> select database_role,log_mode,controlfile_type,protection_mode from v$database;
DATABASE_ROLE LOG_MODE CONTROL PROTECTION_MODE
---------------- ------------ ------- --------------------
PHYSICAL STANDBY ARCHIVELOG STANDBY MAXIMUM PERFORMANCE
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This is also the view that should be checked in switchover and failover.
Refer to SWITCHOVER_STATUS in v$database to check if it is ready for switchover process.
To confirm the REDO log destination
By referring to init file, the REDO log destination is shown in log_archive_dest_n. In Oracle, it can be confirmed in v$archive_dest view.
SQL> select destination,status,target,archiver,process from v$archive_dest;
DESTINATION STATUS TARGET ARCHIVER PROCESS
------------------------------------ --------- ------- ---------- ----------
/home/oracle/archive VALID LOCAL ARCH ARCH
standby.world VALID REMOTE LGWR LGWR
primary.world VALID REMOTE LGWR LGWR
INACTIVE LOCAL ARCH ARCH
INACTIVE LOCAL ARCH ARCH
INACTIVE LOCAL ARCH ARCH
INACTIVE LOCAL ARCH ARCH
INACTIVE LOCAL ARCH ARCH
INACTIVE LOCAL ARCH ARCH
INACTIVE LOCAL ARCH ARCH
/home/oracle/archive/standby/standby VALID LOCAL ARCH RFS
11 rows are selected.
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By checking v$archive_dest, we can confirm whether it is LOCAL ARCH or REMOTE LGWR.
To confirm the transmission status
In the case of real-rime application, we would like to know if it is well apllied. Confirm this by checking v$archived_log view.
SELECT SEQUENCE#,APPLIED FROM V$ARCHIVED_LOG ORDER BY SEQUENCE#;
SEQUENCE# APP
---------- ---
9 YES
.........
SEQUENCE# APP
---------- ---
26 YES
27 YES
28 YES
29 YES
30 YES
31 YES
32 YES
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Refer to v$archive_dest_status view to check the current applied method.
SQL> select dest_name,recovery_mode from v$archive_dest_status;
DEST_NAME RECOVERY_MODE
-------------------- -----------------------
LOG_ARCHIVE_DEST_1 MANAGED REAL TIME APPLY
LOG_ARCHIVE_DEST_2 MANAGED REAL TIME APPLY
〜
LOG_ARCHIVE_DEST_10 MANAGED REAL TIME APPLY
STANDBY_ARCHIVE_DEST MANAGED REAL TIME APPLY
11 rows are selected.
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To confirm the transmission process status
The information about transmission process can be checked by referring to v$managed_standby view.
SQL> select PROCESS,PID,STATUS,CLIENT_PROCESS,CLIENT_PID,
SQL> CLIENT_DBID,RESETLOG_ID,SEQUENCE#,DELAY_MINS,ACTIVE_AGENTS
SQL> from v$managed_standby;
PROCESS PID STATUS CLIENT_P CLIENT_PID RESETLOG_ID SEQUENCE# DELAY_MINS ACTIVE_AGENTS
--------- ------- ----------- -------- ---------- ----------- ---------- ---------- -------------
ARCH 7863 CONNECTED ARCH 7863 0 0 0 0
ARCH 7865 CONNECTED ARCH 7865 0 0 0 0
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Execute alter database switch logfile in the primary database.
SQL> alter system switch logfile;
System changed.
SQL> select PROCESS,PID,STATUS,CLIENT_PROCESS,CLIENT_PID,
SQL> CLIENT_DBID,RESETLOG_ID,SEQUENCE#,DELAY_MINS,ACTIVE_AGENTS
SQL> from v$managed_standby;
PROCESS PID STATUS CLIENT_P RESETLOG_ID SEQUENCE# DELAY_MINS ACTIVE_AGENTS
--------- ---------- ------------ -------- ----------- ---------- ---------- -------------
ARCH 7863 CONNECTED ARCH 0 0 0 0
ARCH 7865 CONNECTED ARCH 0 0 0 0
RFS 8291 WRITING LGWR 529269042 95 0 0
RFS 8293 RECEIVING UNKNOWN 0 0 0 0
RFS 8295 ATTACHED UNKNOWN 0 0 0 0
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We can see that RFS (Remote File Server) is in the writing process.
That's it for today. We will start a new topic next week. Please look forward to it!
Masaru Hayashi
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