Troubleshooting Guide

Understanding First Failure Data Capture

First Failure Data Capture (FFDC) information is diagnostic information captured automatically by DB2 about an error when the error occurs. This information reduces the need to reproduce errors to get diagnostic information.

The information captured by FFDC includes the following:

db2diag.log

When an error occurs, the db2diag.log file is updated with information about the error. For information, see "Interpreting the db2diag.log File". Also see "Setting DIAGLEVEL and DIAGPATH" for information on the DIAGLEVEL setting, which determines how much information is logged in the file.

db2alert.log

If an error is determined to be an alert, then an entry is made in the db2alert.log file and to the operating system/native logging facility. See "Alerts".

Dump files

For some error conditions, extra information is logged in external binary dump files named after the failing process ID. These files are intended for DB2 Customer Service. See "Dump Files".

Trap files

The database manager generates a trap file if it cannot continue processing because of a trap, segmentation violation, or exception (depending on the platform). Trap files contain a function flow of the last steps that were executed before a problem occurred. See "Trap Files".

This diagnostic information is contained in a single location (the DIAGPATH specified in the database manager configuration). It contains internal traces and dumps which usually can be read only by trained DB2 Customer Service personnel. However, this information can contain some crucial information to help you diagnose and fix problems.

Setting DIAGLEVEL and DIAGPATH

The following database manager configuration parameters affect how much FFDC information is collected, and where it is kept:

• DIAGLEVEL specifies the level of diagnostic information you will receive. The following data is captured for each DIAGLEVEL value:
  • DIAGLEVEL (0) - no diagnostic data (this level is not recommended)
  • DIAGLEVEL (1) - severe errors only
  • DIAGLEVEL (2) - all errors (severe and not severe)
  • DIAGLEVEL (3) - all errors and warnings (the default value)
  • DIAGLEVEL (4) - all errors, warnings, informational messages, and other internal diagnostic information

  The default for DIAGLEVEL is 3. Change it to 4 during initial setup, and during those times when you are experiencing problems.

• DIAGPATH specifies the fully qualified path where DB2 writes its diagnostic information. This directory contains dump, error log, and alert log files, and is created automatically.

  The default for DIAGPATH is a null string. It is recommended that you use this default value or use a centralized location, especially if there are multiple database instances. By default, the FFDC information is placed in the following locations:

  • For Windows and OS/2:

    • If the DB2INSTPROF environment variable is not set: db2path\db2instance (where db2path is the path referenced in the DB2PATH environment variable, and db2instance is the environment variable containing the ID of the instance owner)

    • If the DB2INSTPROF environment variable is set: x:\db2instprof\db2instance (where x is the drive referenced in the DB2PATH environment variable, db2instprof is the instance profile directory, and db2instance is the environment variable containing the ID of the instance owner)

  • For UNIX-based environments: $HOME/sqllib/db2dump, where $HOME is the home directory of the instance owner.

To set these configuration parameters, use the UPDATE DATABASE MANAGER CONFIGURATION command from the command line processor. (Alternatively, use the Problem Determination folder for the OS/2 platform; see Appendix A. "Using the Problem Determination Tools Folder" for information.)

Important: You must stop DB2 and start it again before any of these configuration changes take effect.

Examples

• To obtain the most diagnostic information, type:

  db2 "UPDATE DATABASE MANAGER CONFIGURATION USING DIAGLEVEL 4"
  

• To set the diagnostic path to a new directory called x:\tmp\errors, type:

  db2 "UPDATE DATABASE MANAGER CONFIGURATION USING DIAGPATH x:\tmp\errors"
  

• To reset the diagnostic path to the default, type:

  db2 "UPDATE DATABASE MANAGER CONFIGURATION USING DIAGPATH NULL"
  

For information on database manager administration commands, see the Administration Guide, the Command Reference, and the API Reference.

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