----恢复丢失当前使用重做日志文件状况下的数据库：

---查看日志文件的信息：

sys@PROD>col member for a50

sys@PROD>select group#,member from v$logfile;

    GROUP# MEMBER

---------- --------------------------------------------------

         3 /u01/app/oracle/oradata/PROD/redo03.log

         2 /u01/app/oracle/oradata/PROD/redo02.log

         1 /u01/app/oracle/oradata/PROD/redo01.log

#共有三个日志文件组，每个组只有一个日志成员。

 ---查看日志组的状态：

sys@PROD>

sys@PROD>select group#,status from v$log;

    GROUP# STATUS

---------- ----------------

         1 INACTIVE

         2 INACTIVE

         3 CURRENT

#当前正在使用的是第三号日志文件组。

---查看当前的数据库模式：

sys@PROD>archive log list;

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     13

Next log sequence to archive   15

Current log sequence           15

#当前数据库处于归档模式，如果不是归档模式，需要调至归档模式。

---给每个日志组添加一个日志成员：

sys@PROD>Alter database add logfile member

  2  '/u01/app/oracle/oradata/PROD/redo01b.log' to group 1;

Database altered.

sys@PROD>Alter database add logfile member

  2  '/u01/app/oracle/oradata/PROD/redo02b.log' to group 2;

Database altered.

sys@PROD>Alter database add logfile member

  2  '/u01/app/oracle/oradata/PROD/redo03b.log' to group 3;

Database altered.

#日志文件成功添加完成，添加的日志文件成员默认的大小与该组原有的成员的大小一致。

当在添加日志组的时候，需要指定日志文件成员的大小。

---再次查看日志文件信息：

sys@PROD>select group#,member from v$logfile;

    GROUP# MEMBER

---------- --------------------------------------------------

         3 /u01/app/oracle/oradata/PROD/redo03.log

         2 /u01/app/oracle/oradata/PROD/redo02.log

         1 /u01/app/oracle/oradata/PROD/redo01.log

         1 /u01/app/oracle/oradata/PROD/redo01b.log

         2 /u01/app/oracle/oradata/PROD/redo02b.log

         3 /u01/app/oracle/oradata/PROD/redo03b.log

#日志成员添加成功。

---查看日志组与成员的信息：

sys@PROD>select group#,status,members,bytes/1024/1024 Mbytes

  2  from v$log;

    GROUP# STATUS              MEMBERS     MBYTES

---------- ---------------- ---------- ----------

         1 INACTIVE                  2         50

         2 INACTIVE                  2         50

         3 CURRENT                   2         50

#当前使用的是第三组日志文件，每个日志组包括两个日志成功，每个日志文件的大小为50M。

---删除当前使用日志组的一个日志成员：

/u01/app/oracle/oradata/PROD/redo03b.log

sys@PROD>!rm /u01/app/oracle/oradata/PROD/redo03b.log

sys@PROD>!ls /u01/app/oracle/oradata/PROD/redo03b.log

ls: /u01/app/oracle/oradata/PROD/redo03b.log: No such file or directory

#删除完成。

---致性关库并重新打开：

sys@PROD>shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

sys@PROD>startup

ORACLE instance started.

Total System Global Area  835104768 bytes

Fixed Size                  2257840 bytes

Variable Size             507513936 bytes

Database Buffers          322961408 bytes

Redo Buffers                2371584 bytes

Database mounted.

ORA-03113: end-of-file on communication channel

Process ID: 5748

Session ID: 1 Serial number: 5

----尝试切换日志文件：

[oracle@enmo ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Fri Nov 18 11:06:44 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

PROD>startup mount;

ORACLE instance started.

Total System Global Area  835104768 bytes

Fixed Size                  2257840 bytes

Variable Size             507513936 bytes

Database Buffers          322961408 bytes

Redo Buffers                2371584 bytes

Database mounted.

PROD>alter system switch logfile;

alter system switch logfile

*

ERROR at line 1:

ORA-01109: database not open

---通过rman查看文件错误信息：

[oracle@enmo ~]$ rman target /

Recovery Manager: Release 11.2.0.4.0 - Production on Fri Nov 18 11:09:32 2016

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

connected to target database: PROD (DBID=338469376, not open)

RMAN>

RMAN> list failure;

using target database control file instead of recovery catalog

List of Database Failures

=========================

Failure ID Priority Status    Time Detected Summary

---------- -------- --------- ------------- -------

2025       CRITICAL OPEN      18-NOV-16     Redo log group 3 is unavailable

2022       HIGH     OPEN      18-NOV-16     Redo log file /u01/app/oracle/oradata/PROD/redo03.log is corrupt

---通过rman查看恢复丢失文件的建议：

RMAN>  advise failure;

List of Database Failures

=========================

Failure ID Priority Status    Time Detected Summary

---------- -------- --------- ------------- -------

2025       CRITICAL OPEN      18-NOV-16     Redo log group 3 is unavailable

2022       HIGH     OPEN      18-NOV-16     Redo log file /u01/app/oracle/oradata/PROD/redo03.log is corrupt

analyzing automatic repair options; this may take some time

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=20 device type=DISK

analyzing automatic repair options complete

Mandatory Manual Actions

========================

no manual actions available

Optional Manual Actions

=======================

no manual actions available

Automated Repair Options

========================

Option Repair Description

------ ------------------

1      Open resetlogs  

  Strategy: The repair includes complete media recovery with no data loss

---利用rman通过修复建议修复丢失的文件：

RMAN>  repair failure;

Strategy: The repair includes complete media recovery with no data loss

Repair script: /u01/app/oracle/diag/rdbms/prod/PROD/hm/reco_3535562984.hm

contents of repair script:

   # recover database until cancel and open resetlogs

   sql 'alter database recover database until cancel';

   alter database open resetlogs;

Do you really want to execute the above repair (enter YES or NO)? yes

executing repair script

sql statement: alter database recover database until cancel

database opened

repair failure complete

---修复完成并打开数据库：

PROD>select status from v$instance;

STATUS

------------

OPEN

#数据库已经处于打开状态。