期间主库日志：
Sun Apr 20 16:23:25 2014
Thread 1 advanced to log sequence 44
Current log# 2 seq# 44 mem# 0: /u01/app/oracle/prod/disk1/redo02.log
Current log# 2 seq# 44 mem# 1: /u01/app/oracle/prod/disk2/log2b.log
Sun Apr 20 16:23:25 2014
ARC0: Standby redo logfile selected for thread 1 sequence 43 for destination LOG_ARCHIVE_DEST_2
Sun Apr 20 16:25:06 2014
Thread 1 advanced to log sequence 45
Current log# 3 seq# 45 mem# 0: /u01/app/oracle/prod/disk1/redo03.log
Current log# 3 seq# 45 mem# 1: /u01/app/oracle/prod/disk2/log3b.log
Sun Apr 20 16:25:06 2014
ARC0: Standby redo logfile selected for thread 1 sequence 44 for destination LOG_ARCHIVE_DEST_2
##此期间备库日志：
Managed Standby Recovery Canceled (PROD1)
Sun Apr 20 04:23:17 2014
Completed: alter database recover managed standby database cancel
Sun Apr 20 04:23:20 2014
RFS[8]: Successfully opened standby log 4: '/u01/app/oracle/prod/disk1/standbylog1.log'
Sun Apr 20 04:25:01 2014
RFS[8]: Successfully opened standby log 4: '/u01/app/oracle/prod/disk1/standbylog1.log'
实验5：主库修改参数为：lgwr async,备库有STANDBY LOG 总结：此时
主库上操作：
16:28:46 SQL> show parameter log_archive_dest_2
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_2 string SERVICE=prod1 lgwr async VALI
D_FOR=(ONLINE_LOGFILES,PRIMARY
_ROLE) DB_UNIQUE_NAME=prod1
16:28:47 SQL> alter system switch logfile;
System altered.
16:30:06 SQL> select max(sequence#) from v$archived_log;
MAX(SEQUENCE#)
--------------
45
16:30:36 SQL> alter system switch logfile;
System altered.
16:30:45 SQL> select max(sequence#) from v$archived_log;
MAX(SEQUENCE#)
--------------
46
16:33:08 SQL> alter system switch logfile;
System altered.
16:33:09 SQL> select max(sequence#) from v$archived_log;
MAX(SEQUENCE#)
--------------
47
备库上查询：
04:29:17 SQL> alter database recover managed standby database disconnect from session;
Database altered.
04:29:32 SQL> select max(sequence#) from v$archived_log;
MAX(SEQUENCE#)
--------------
46
04:30:44 SQL> select max(sequence#) from v$archived_log;
MAX(SEQUENCE#)
--------------
46
04:33:09 SQL> select max(sequence#) from v$archived_log;
MAX(SEQUENCE#)
--------------
47
############
此期间主库日志：
Sun Apr 20 16:28:25 2014
ALTER SYSTEM SET log_archive_dest_2='SERVICE=prod1 lgwr async VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=prod1' SCOPE=BOTH;
LNS1 started with pid=16, OS id=12273
Sun Apr 20 16:30:06 2014
Thread 1 advanced to log sequence 46
Current log# 1 seq# 46 mem# 0: /u01/app/oracle/prod/disk1/redo01.log
Current log# 1 seq# 46 mem# 1: /u01/app/oracle/prod/disk2/log1b.log
Sun Apr 20 16:30:06 2014
ARC0: Standby redo logfile selected for thread 1 sequence 45 for destination LOG_ARCHIVE_DEST_2
Sun Apr 20 16:30:07 2014
******************************************************************
LGWR: Setting 'active' archival for destination LOG_ARCHIVE_DEST_2
******************************************************************
LNS: Standby redo logfile selected for thread 1 sequence 46 for destination LOG_ARCHIVE_DEST_2
Sun Apr 20 16:30:42 2014
Thread 1 cannot allocate new log, sequence 47
Checkpoint not complete
Current log# 1 seq# 46 mem# 0: /u01/app/oracle/prod/disk1/redo01.log
Current log# 1 seq# 46 mem# 1: /u01/app/oracle/prod/disk2/log1b.log
Thread 1 advanced to log sequence 47
Current log# |