【练习---日志文件的恢复】-----多元化成员中，单个成员丢失

1.查看当前的日志组成员：

09:59:28 SYS@ORA11GR2>select group#,member from v$logfile;

    GROUP# MEMBER
---------- --------------------------------------------------
         3 /u01/app/oracle/oradata/ORA11GR2/redo03.log
         2 /u01/app/oracle/oradata/ORA11GR2/redo02.log
         1 /u01/app/oracle/oradata/ORA11GR2/redo01.log

09:59:42 SYS@ORA11GR2>select group#,members,bytes/1024/1024 M,status from v$log;

    GROUP#    MEMBERS          M STATUS
---------- ---------- ---------- ----------------
         1          1         50 CURRENT
         2          1         50 INACTIVE
         3          1         50 INACTIVE

2.给每个日志组增加一个成员：

09:59:49 SYS@ORA11GR2>alter database add logfile member 
10:00:24   2  '/u01/app/oracle/disk/redo03b.log' to group 3;

Database altered.

10:01:13 SYS@ORA11GR2>alter database add logfile member
10:01:25   2  '/u01/app/oracle/disk/redo02b.log' to group 2;

Database altered.

10:02:30 SYS@ORA11GR2>alter database add logfile member
10:02:42   2  '/u01/app/oracle/disk/redo01b.log' to group 1;

Database altered.

3.现在有三个日志组，每组都有两个成员：

10:02:53 SYS@ORA11GR2>select group#,member from v$logfile;

    GROUP# MEMBER
---------- --------------------------------------------------
         3 /u01/app/oracle/oradata/ORA11GR2/redo03.log
         2 /u01/app/oracle/oradata/ORA11GR2/redo02.log
         1 /u01/app/oracle/oradata/ORA11GR2/redo01.log
         3 /u01/app/oracle/disk/redo03b.log
         2 /u01/app/oracle/disk/redo02b.log
         1 /u01/app/oracle/disk/redo01b.log

6 rows selected.

3.[oracle@host03 ~]$ ls /u01/app/oracle/disk
redo01b.log  redo02b.log  redo03b.log

4.关库删除一个日志组成员：

10:04:21 SYS@ORA11GR2>shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
[oracle@host03 ~]$ rm /u01/app/oracle/disk/redo03b.log

5.起库，不会报错：

10:05:28 SYS@ORA11GR2>startup 
ORACLE instance started.

Total System Global Area  830930944 bytes
Fixed Size                  2257800 bytes
Variable Size             536874104 bytes
Database Buffers          289406976 bytes
Redo Buffers                2392064 bytes
Database mounted.
Database opened.

6.但是看alert日志，会有找不到redo03b.log的日志文件

ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/u01/app/oracle/disk/redo03b.log'
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
10:10:13 SYS@ORA11GR2>select group#,member,status from v$logfile;

    GROUP# MEMBER                                             STATUS
---------- -------------------------------------------------- -------
         3 /u01/app/oracle/oradata/ORA11GR2/redo03.log
         2 /u01/app/oracle/oradata/ORA11GR2/redo02.log
         1 /u01/app/oracle/oradata/ORA11GR2/redo01.log
         3 /u01/app/oracle/disk/redo03b.log                   INVALID
         2 /u01/app/oracle/disk/redo02b.log
         1 /u01/app/oracle/disk/redo01b.log

6 rows selected.

7.解决办法：

关库
10:12:35 SYS@ORA11GR2>shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
系统层面拷贝一个
[oracle@host03 ~]$ cp /u01/app/oracle/disk/redo01b.log /u01/app/oracle/disk/redo03b.log
此时起库alert日志里也没有错误信息了
10:19:19 SYS@ORA11GR2>alter system switch logfile;

System altered.

10:20:17 SYS@ORA11GR2>select group#,member,status from v$logfile;

    GROUP# MEMBER                                             STATUS
---------- -------------------------------------------------- -------
         3 /u01/app/oracle/oradata/ORA11GR2/redo03.log
         2 /u01/app/oracle/oradata/ORA11GR2/redo02.log
         1 /u01/app/oracle/oradata/ORA11GR2/redo01.log
         3 /u01/app/oracle/disk/redo03b.log
         2 /u01/app/oracle/disk/redo02b.log
         1 /u01/app/oracle/disk/redo01b.log

6 rows selected.