[bbk5361] 第86集 -第11章 -数据库诊断 02

数据库恢复专家，在进行修复的时候，有2个项选，其中之一是无损修复，另外一种是有损修复，可供DBA选择.

执行ADVISE FAILURE与REPAIR FAILURE命令，必须是在同一个SESSION当中.修复工作，是无法并发操作的.

使用数据库恢复专家，有两种途径：OEM方式及Manual方式，接下来介绍一下Manual方式

Listing Data Failures

The RMAN LIST FAILURE command lists previously executed failure assessment.

• Including newly diagnosed failures
• Removing closed failures(by default)

Syntax:

LIST FAILURE

[ ALL | CRITICAL | HIGH | LOW | CLOSED | failnum[,failnum,...]] 

[ EXCLUDE FAILURE failnum[,failnum,...]]

[DETAIL]

Advising on Repair

The RMAN ADVISE FAILURE command:

• Displays a summary of input failure list
• Includes a warning,if new failures appeared in ADR
• Displays a manula checklist
• Lists a single recommended repair option
• Generates a repair script(for automatic or manual repair)

 

Executing Repairs

The RMAN REPAIR FAILURE command:

• Follows the ADVISE FAILURE command
• Repairs the specified failure
• Closes the repaired failure

Syntax:

REPAIR FAILURE

[USING ADVISE OPTION integer]

[ {{NOPROMPT | PREVIEW}}... ] 

 

Classifying(and Closing) Failures

The RMAN CHANGE FAILURE command:

• Changes the failure priority(except for CRITICAL)(CHANGE FAILURE命令，可以将HIGH级别的故障，修改成LOW级别的故障.但是不可以将CRITICAL级别的故障，修改成HIGH级别的故障.)
• Closes one or more failures

Example:

Data Recovery Advisor Views

Querying V$ views:(查看动态性能视图，查看数据库恢复专家相关的动态性能视图)

• V$IR_FAILURE:List of all failures,including closed ones(result of the LIST FAILURE command)
• V$IR_MANULA_CHECKLIST:List of manual advice(result of the ADVISE FAILURE command)
• V$IR_REPAIR:List of repairs(result of the ADVISE FAILURE command)
• V$IR_FAILURE_SET:Cross-reference of failure and advice identifiers

Best Practice:Proactive Checks

DBA具备前瞻性的眼光，提前进行健康检查（主动防御、主动检查）

Invoking proactive health check of the database and its components:

• Health Monitor or RMAN VALIDATE DATABAES command
• Checking for logical and physical corruption
• Finding logged in the ADR