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OCP考题解析_042:控制文件的备份和转储

OCP考题解析_042:控制文件的备份和转储
 
  ㈠ 备份
         www.zzzyk.com  
       控制文件的备份和恢复在数据库的备份恢复过程中十分关键
       原则是:
       在数据库物理结构发生变化后备份控制文件
       方法有:
       ① 通过操作系统命令在数据库关闭时对控制文件进行COPY
       
          一般用于全库一致性恢复
          
       ② 利用ALTER DATABASE BACKUP CONTROLFILE TO命令将控制文件备份到二进制文件  www.zzzyk.com  
          
          Oracle推荐使用这种方式来备份控制文件、这也是最简单的方式、比如:
          ALTER DATABASE BACKUP CONTROLFILE TO '/home/oracle/control01.bak';
          
       ③ 利用ALTER DATABASE BACKUP CONTROLFILE TO TRACE命令将重建控制文件备份的脚本备份到后台trace文件中
          
          这种方式备份控制文件会丢失归档日志历史等许多信息
          在重建控制文件时,只读表空间和脱机的数据文件的处理相对比较复杂
          比如,OCP_043有道题目:
[sql] 
3. One of the tablespace is read-only in your database. The loss of all   
control file forced you to recreate the control file. Which operation do   
you need to perform after re-creating the control file and opening the   
database?   
  
A. Drop and re-create the read-only tablespaces   
B. Rename the read-only data file to their correct file names.   
C. Change the tablespace status from read/write to read-only.   
D. Re-create the read-only tablespace because it is automatically removed.  
   
Answer: B   
 
       ㈡ 转储
          
          oradebug必须以SYSDBA形式登陆后方能使用,可参看:oradebug使用介绍
 
 
[sql] 
idle> conn / as sysdba  
Connected.  
sys@ORCL> oradebug setmypid  
Statement processed.  
sys@ORCL> oradebug dump controlf 3;      
Statement processed.  
sys@ORCL> oradebug tracefile_name;  
/u01/app/oracle/admin/orcl/udump/orcl_ora_7489.trc  
 
       ㈢ OCP考题
[sql] 
4. You backed up the control file to trace. Which statement is true about the trace file generated?   
  
A. The trace file is in binary format.   
B. The trace file has a SQL scripts to re-create the control file.   
C. The trace file is a backup set created during the backup of the control file.   
D. The trace file contains the instructions to manually re-create the control file.   
E. The trace file is an image copy of the control file created during the backup of   
the the control file.   
  
answer: B   
 
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