OCP考题解析_042:控制文件的备份和转储
㈠ 备份
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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
