3，重建redo log
再查看下看一下现在的redo log状态
select group#,bytes/1024/1024,members,status from v$log;
SQL> select group#,bytes/1024/1024,members,status from v$log;
GROUP# BYTES/1024/1024 MEMBERS STATUS
---------- --------------- ---------- ----------------
1 50 1 UNUSED
2 50 1 CLEARING
3 50 1 CLEARING_CURRENT
redo log损坏，但是clear不管用，因为是备库 read-only不让切换日志
重建redo日志文件，先停redo应用
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
alter database add logfile group 4 ('/home/oradata/powerdes/redo04.log') size 50M;
alter database add logfile group 5 ('/home/oradata/powerdes/redo05.log') size 50M;
alter database add logfile group 6 ('/home/oradata/powerdes/redo06.log') size 50M;
日志管理是自动的，所以不能操作，要先设置成手动管理的
SQL> alter system set standby_file_management='manual';
System altered.
SQL> alter database add logfile group 4 ('/home/oradata/powerdes/redo04.log') size 50M;
Database altered.
SQL> alter database add logfile group 5 ('/home/oradata/powerdes/redo05.log') size 50M;
Database altered.
SQL> alter database add logfile group 6 ('/home/oradata/powerdes/redo06.log') size 50M;
Database altered.
SQL>
查看一下日志状态
SQL> select group#,bytes/1024/1024,members,status from v$log;
GROUP# BYTES/1024/1024 MEMBERS STATUS
---------- --------------- ---------- ----------------
1 50 1 CLEARING_CURRENT
2 50 1 CLEARING
3 50 1 CLEARING
4 50 1 UNUSED
5 50 1 UNUSED
6 50 1 UNUSED
6 rows selected.
清空redo日志组
SQL>
alter database clear logfile group 1;
alter database clear logfile group 2;
alter database clear logfile group 3;
SQL>
alter database clear logfile group 1;
alter database clear logfile group 2;
alter database clear logfile group 3;
Database altered.
SQL>
Database altered.
SQL>
Database altered.
SQL>
查看redo 日志组信息
SQL> select group#,bytes/1024/1024,members,status from v$log;
GROUP# BYTES/1024/1024 MEMBERS STATUS
---------- --------------- ---------- ----------------
1 50 1 CURRENT
2 50 1 UNUSED
3 50 1 UNUSED
4 50 1 UNUSED
5 50 1 UNUSED
6 50 1 UNUSED
6 rows selected.
alter database drop logfile group 1;
alter database drop logfile group 2;
alter database drop logfile group 3;
SQL>
alter database drop logfile group 1;
alter database drop logfile group 2;
alter database drop logfile group 3;
Database altered.
SQL>
Database altered.
SQL> alter database drop logfile group 3
*
ERROR at line 1:
ORA-01623: log 3 is current log for instance powerdes (thread 1) - cannot drop
ORA-00312: online log 3 thread 1: '/home/oradata/powerdes/redo03.log'
SQL>
4，检查归档文件是否完整
从库redo log损坏了的话，只要从库的归档日志在，还是可以修复的，不用重新做Standy。
从库上执行check：
SQL> SELECT DISTINCT THREAD#,max(SEQUENCE#) OVER(PARTITION BY THREAD#) A FROM V$ARCHIVED_LOG;
THREAD# A
---------- ----------
1 23826
SQL>
主库上执行check：
SQL> SELECT DISTINCT THREAD#,max(SEQUENCE#) OVER(PARTITION BY THREAD#) A FROM V$ARCHIVED_LOG;
THREAD# A
---------- ----------
1 24022
SQL>
取出primary和standy库上各线程已经归档文件最大序列号，看到两者不相同，必须将多出的序列号对应的归档文件复制到standy库。
也就是说主库从库的归档日志相差蛮大的。
如何查看归档路径，最高可用模式的时候 dg会尽力的让日志应用到standby
去查一下
SELECT GROUP#,THREAD#,SEQUENCE#,ARCHIVED,STATUS FROM V$STANDBY_LOG;
从库：
SQL> SELECT GROUP#,THREAD#,SEQUENCE#,ARCHIVED,STATUS FROM V$STANDBY_LOG;
no rows selected
SQL>
主库：
SQL> SELECT GROUP#,THREAD#,SEQUENCE#,ARCHIVED,STATUS FROM V$STANDBY_LOG;
no rows selected
SQL>
表名从库的standby log都空的，需要重建standby log。