[每天一题] 11gOCP 1z0-053 :2013-10-6 significance of the CHANGE FAILURE .25

2013-10-08

[每日一题]11gOCP 1z0-053 :2013-10-6significance of the CHANGE FAILURE ..................25转载请注

[每日一题] 11gOCP 1z0-053 :2013-10-6 significance of the CHANGE FAILURE ..................25

转载请注明出处：http://blog.csdn.net/guoyjoe/article/details/12361287

正确答案：AD

来自官方对CHANGE FAILURE command的语法解释，如下图所示：

[每天一题] 11gOCP 1z0-053 :2013-10-6 significance of the CHANGE FAILURE .25

changeFailure

This clause enables you to change the status of failures. Use the LIST FAILURE command to show the list of failures.

Syntax Element

Description

FAILURE

Enables you to change priority or close failures recorded in the Automatic Diagnostic Repository. By default RMAN prompts for confirmation before performing the requested change.

The target database to which RMAN is connected must be a single-instance database and must not be a physical standby database.

ALL

Changes only open failures.

CRITICAL

Changes only critical failures.

HIGH

Changes only failures with HIGH priority.

LOW

Changes only failures with LOW priority.

failnum

Changes only the specified failure.

EXCLUDE FAILURE
failnum

Excludes the specified failures from the change.

CHANGE FAILURE 命令用于更改故障优先级或关闭一个或多个故障，只能将故障优先级从HIGH 更改为LOW 和从LOW 更改为HIGH。当更改CRITICAL 优先级时会出现错误。（将故障的优先级从HIGH 更改为LOW 的一个原因是为了避免该故障显示在LIST FAILURE 命令的默认输出列表中。例如，如果块损坏具有HIGH 优先级，则该块位于很少使用的表空间中时，您可能希望将其临时更改为LOW。）修复故障后，将隐式关闭打开的故障。但是，也可以显式关闭故障。这需要重新评估其它所有打开的故障，因为其中的某些故障会因故障关闭而变得不相关。默认情况下，该命令要求用户确认请求的更改。

实验测试：

1、用rman登录备份数据库

2、 删除某个数据文件
、 数据库宕机
3、 数据库宕机
 启动数据库到mount;
RMAN> startup mount;connected to target database (not started)Oracle instance starteddatabase mountedTotal System Global Area     839282688 bytesFixed Size                     2233000 bytesVariable Size                436211032 bytesDatabase Buffers             394264576 bytesRedo Buffers                   6574080 bytes

5、  Listfailure 命令会显示任何open 状态的failures，并会优先显示critical 或high的failure，如果没有类似的failure，那么会显示low 的failures。
     RMAN> alter database open;RMAN-00571: ===========================================================RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============RMAN-00571: ===========================================================RMAN-03002: failure of alter db command at 10/06/2013 22:43:30ORA-01157: cannot identify/lock data file 7 - see DBWR trace fileORA-01110: data file 7: '/u01/app/oracle/oradata/ocm/gyj02.dbf'RMAN>  LIST FAILURE;List of Database Failures=========================Failure ID Priority Status    Time Detected Summary---------- -------- --------- ------------- -------
    2002       HIGH     OPEN      06-OCT-13     One or more non-system datafiles are missing

6、 从上面的failure级别看是high，我现在用Changefailure 命令改变failure的级别为low。如果有一个failure，在我们没有修复之前，或者暂时不想修复，那么我们就可以调低它的级别，级别的修改不影响系统的正常使用。
7、 级别改低后，就不在修复的范围内了，但不影响其它恢复
    RMAN> LIST FAILURE;using target database control file instead of recovery catalogno failures found that match specification

8、 显式地关闭，即恢复到原来的级别（从LOW到HIGH）
9、恢复数据库，并打开数据库
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[每天一题] 11gOCP 1z0-053 :2013-10-6 significance of the CHANGE FAILURE .25