[ORACLE][RMAN]關鍵資料庫(SYSTEM及UNDO)災難復原

資料庫環境確認
1. Instance已經不正常結束
    sqlplus / as sysdba
    startup mount;

2. Instance尚在Open的狀況下
    2.1 還可以進入資料庫的情況下
          2.1.1 登入資料庫不會出現錯誤訊息
                   sqlplus / as sysdba
                   shutdown abort;
          2.1.2 登入資料庫但卻連到idle instance
                   直接KILL process，例如：kill SMON

3. 已無法進入資料庫
    直接KILL process，例如：kill SMON

P.S.：此篇復原前提為參數檔(init)，控制檔(controlfile)，archivelog，redo log皆正常的情形下。

復原流程：
1. 使用shutdown abort或是KILL process關閉資料庫
2. 執行startup mount;將資料庫啟動到Mount
3. 使用RMAN執行restore或是switch命令還原有問題的SYSTEM file或UNDO file
4. 使用RMAN執行recover database，透過archivelog及redolog復原資料庫
5. 執行alter database open開啟資料庫

復原詳細過程
1. 關閉資料庫
SQL> shutdown abort;
ORACLE instance shut down.

2. 啟動資料庫，發現有datafile毀損
SQL> startup;
ORACLE instance started.
Total System Global Area 3340451840 bytes
Fixed Size      2257840 bytes
Variable Size   1879051344 bytes
Database Buffers  1442840576 bytes
Redo Buffers     16302080 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 1 - see DBWR trace file
ORA-01110: data file 1: '/u01/app/oracle/oradata/orclnofra/system01.dbf'

3. 檢查TRACE LOG
log路徑：/u01/app/oracle/diag/rdbms/orclnofra/orclnofra/trace/alert_orclnofra.log
log擷取部分錯誤如下

4. 透過restore database還原data file 1
RMAN> restore datafile 1;  
Starting restore at 25-APR-2016 17:28:00
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=129 device type=DISK
channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00001 to /u01/app/oracle/oradata/orclnofra/system01.dbf
channel ORA_DISK_1: reading from backup piece /backup/ORCLNOFR_20160425_6_1.bak
channel ORA_DISK_1: piece handle=/backup/ORCLNOFR_20160425_6_1.bak tag=TAG20160425T171813
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:15
Finished restore at 25-APR-2016 17:28:15

5. 執行recover database
RMAN> recover database;
Starting recover at 25-APR-2016 17:28:55
using channel ORA_DISK_1
starting media recovery
media recovery complete, elapsed time: 00:00:01
Finished recover at 25-APR-2016 17:28:56

6. 將資料庫OPEN
RMAN> alter database open;
database opened

7. 查看datafile是否OK
SQL> select name from v$datafile;
NAME
--------------------------------------------------------------------------------
/u01/app/oracle/oradata/orclnofra/system01.dbf
/u01/app/oracle/oradata/orclnofra/sysaux01.dbf
/u01/app/oracle/oradata/orclnofra/undotbs01.dbf
/u01/app/oracle/oradata/orclnofra/users01.dbf
/backup/test01.dbf
/backup/test02.dbf
6 rows selected.