Oracle Database 11 g - Online Public Access Catalog

CHAPTER 2 ■ DATABASE DIAGNOSABILITY AND FAILURE REPAIR 59Currently, you use the initialization parameters background_dump_dest, core_dump_dest,and user_dump_dest to specify where the database should store all diagnostic data, includingthe all-important alert log file. Starting with the Oracle Database 11g release, all database diagnosticdata will be stored in the new ADR. The great benefit of the ADR is that you can accessthe diagnostic data for a database even when the database is down or can’t be opened forgeneral access because of problems. The ADR stores the diagnostic data not only for all databaseinstances but also for all other Oracle components and features as well, such as automaticstorage management (ASM), Cluster Ready Services (CRS), and others. The ADR uses a consistentdiagnostic data format across these various products.The ADR provides the following benefits in serving as the repository for all the databases’diagnostic data:• A unified directory structure• Consistent diagnostic data formats for diagnostic data not only from multiple Oracleinstances but also from multiple products• The same set of tools to analyze diagnostic data across instancesThe ADR consists of all the familiar Oracle database diagnostic files, such as the following:• The alert log• Trace files• Core and dump filesIn addition to the previously mentioned diagnostic files, the ADR contains new OracleDatabase 11g release diagnostic data such as the following:• Incident packages• SQL test cases• Data repair records■Note In Oracle Database 11g, you can no longer read the alert log that is located in the $ORACLE_BASE/diag/rdbms/$INSTANCE_NAME/$ORACLE_SID/alert directory directly, since it is now an XML file (named log.xml),not text file. In addition to all the standard information regarding database operation, the alert log will now alsocontain information regarding incidents. The alert log file you are used to seeing in previous versions of Oracleis located in the $ORACLE_BASE/diag/rdbms/$INSTANCE_NAME/$ORACLE_SID/trace directory.We advise DBAs to quickly transition to the ADR. DBAs are accustomed to Oracle’s OptimalFlexible Architecture and the standard set of directories in the $ORACLE_BASE/admin/$ORACLE_SIDdirectories. The ADR’s new directory structures and the newly implemented XML alert log filewill take a little time for DBAs to get used to using. On a positive note, the ADR implements astandard layout for DBAs no matter who originally set up the server, and every server will havethe same look and feel for directory structures as they move from one server to another.