Alert Log

Fault Diagnosability Infrastructure Components

The following are the key components of the fault diagnosability infrastructure:

• Automatic Diagnostic Repository (ADR)

• Alert Log

• Trace Files, Dumps, and Core Files

• Other ADR Contents

• Enterprise Manager Support Workbench

• ADRCI Command-Line Utility

 

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.

Note:

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.

See Also:

"Structure, Contents, and Location of the Automatic Diagnostic Repository" for more information on the DIAGNOSTIC_DEST parameter and on ADR homes.

 

Alert Log

The alert log is an XML file that is a chronological log of database messages and errors. It is stored in the ADR and includes messages about the following:

• Critical errors (incidents)

• Administrative operations, such as starting up or shutting down the database, recovering the database, creating or dropping a tablespace, and others.

• Errors during automatic refresh of a materialized view

• Other database events

You can view the alert log in text format (with the XML tags stripped) with Enterprise Manager and with the ADRCI utility. There is also a text-formatted version of the alert log stored in the ADR for backward compatibility. However, Oracle recommends that any parsing of the alert log contents be done with the XML-formatted version, because the text format is unstructured and may change from release to release.

See Also:

• "ADRCI Command-Line Utility"

• "Viewing the Alert Log"

 

Trace Files, Dumps, and Core Files

Trace files, dumps, and core files contain diagnostic data that are used to investigate problems. They are stored in the ADR.

 

Trace Files

Each server and background process can write to an associated trace file. Trace files are updated periodically over the life of the process and can contain information on the process environment, status, activities, and errors. In addition, when a process detects a critical error, it writes information about the error to its trace file. The SQL trace facility also creates trace files, which provide performance information on individual SQL statements. You can enable SQL tracing for a session or an instance.

Trace file names are platform-dependent. Typically, database background process trace file names contain the Oracle SID, the background process name, and the operating system process number, while server process trace file names contain the Oracle SID, the string "ora", and the operating system process number. The file extension is .trc. An example of a server process trace file name is orcl_ora_344.trc. Trace files are sometimes accompanied by corresponding trace map (.trm) files, which contain structural information about trace files and are used for searching and navigation.

Oracle Database includes tools that help you analyze trace files. For more information on application tracing, SQL tracing, and tracing tools, see Oracle Database Performance Tuning Guide.

See Also:

"Finding Trace Files"

 

Dumps

A dump is a specific type of trace file. A dump is typically a one-time output of diagnostic data in response to an event (such as an incident), whereas a trace tends to be continuous output of diagnostic data. When an incident occurs, the database writes one or more dumps to the incident directory created for the incident. Incident dumps also contain the incident number in the file name.

 

Core Files

A core file contains a memory dump, in an all-binary, port-specific format. Core file names include the string "core" and the operating system process ID. Core files are useful to Oracle Support engineers only. Core files are not found on all platforms.

 

Other ADR Contents

In addition to files mentioned in the previous sections, the ADR contains health monitor reports, data repair records, SQL test cases, incident packages, and more. These components are described later in the chapter.

 

link : http://docs.oracle.com/cd/E11882_01/server.112/e25494/diag.htm#CHDFEBHD