题目：

29.Which two statements are true regarding the Automatic Diagnostic Repository (ADR) in Oracle Database 11g? (Choose two.)
A. A single ADR can support multiple ADR homes for different database instances.
B. The alert files are stored in XML file format in the TRACE directory of each ADR home.
C. If the environmental variable ORACLE_BASE is set, then DIAGNOSTIC_DEST is set to $ORACLE_BASE.
D. The BACKGROUND_DUMP_DEST initialization parameter overrides the DIAGNOSTIC_DEST initialization parameter for the location of the alert log file.

参考答案 AC  
解析
ADR它具有跨多个实例和多个产品的统一目录结构 。所以A正确。
alert file的xml文件是存放在alert目录的，而不是trace目录。所以B错误。
如果环境变量ORACLE_BASE设置了，则diagnostic_dest就是$ORACLE_BASE.所以C正确。
该参数在11g中已经被淘汰了。所以D错误。

 

参考文档：

https://docs.oracle.com/cd/E11882_01/server.112/e25494/diag.htm#CHDDHEBD

Automatic Diagnostic Repository (ADR)

The ADR is a file-based repository for database diagnostic data such as traces, dumps, the alert log, health monitor reports, and more. It has a unified directory structure across multiple instances and multiple products. Beginning with Release 11g, the database, Oracle Automatic Storage Management (Oracle ASM), the listener, and other Oracle products or components store all diagnostic data in the ADR. Each instance of each product stores diagnostic data underneath its own home directory within the ADR. For example, in an Oracle Real Application Clusters environment with shared storage and Oracle ASM, each database instance and each Oracle ASM instance has an ADR home directory. ADR's unified directory structure, consistent diagnostic data formats across products and instances, and a unified set of tools enable customers and Oracle Support to correlate and analyze diagnostic data across multiple instances.

Beginning with Release 11g of Oracle Database, because all diagnostic data, including the alert log, are stored in the ADR, the initialization parameters BACKGROUND_DUMP_DEST and USER_DUMP_DEST are deprecated. They are replaced by the initialization parameter DIAGNOSTIC_DEST, which identifies the location of the ADR.

-- 存放位置

[oracle@redhat762100 test]$ cd alert
[oracle@redhat762100 alert]$ ls
log.xml
[oracle@redhat762100 alert]$ pwd
/u01/app/oracle/diag/rdbms/test/test/alert
[oracle@redhat762100 alert]$

[oracle@redhat762100 trace]$ ll *.log
-rw-r-----. 1 oracle oinstall 610185 Aug  9 16:17 alert_test.log
[oracle@redhat762100 trace]$ pwd
/u01/app/oracle/diag/rdbms/test/test/trace
[oracle@redhat762100 trace]$

Structure, Contents, and Location of the Automatic Diagnostic Repository

The Automatic Diagnostic Repository (ADR) is a directory structure that is stored outside of the database. It is therefore available for problem diagnosis when the database is down.

The ADR root directory is known as ADR base. Its location is set by the DIAGNOSTIC_DEST initialization parameter. If this parameter is omitted or left null, the database sets DIAGNOSTIC_DEST upon startup as follows:

• If environment variable ORACLE_BASE is set, DIAGNOSTIC_DEST is set to the directory designated by ORACLE_BASE.

• If environment variable ORACLE_BASE is not set, DIAGNOSTIC_DEST is set to ORACLE_HOME/log.

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