BDUMP, UDUMP, ALERT LOG FILES IN ORACLE 11G

The 11g New Features Guide notes important OFA changes, namely the removal of $ORACLE_HOME as an anchor for diagnostic and alert files:

"The database installation process has been redesigned to be based on the ORACLE_BASE environment variable. Until now, setting this variable has been optional and the only required variable has been ORACLE_HOME.

With this feature, ORACLE_BASE is the only required input, and the ORACLE_HOME setting will be derived from ORACLE_BASE."

Let's take a look at changes to the Oracle11g OFA standard.

Enter new admin subdirectories

New in Oracle 11g we see the new ADR (Automatic Diagnostic Repository) and Incident Packaging System, all designed to allow quick access to alert and diagnostic information.

The new $ADR_HOME directory is located by default at $ORACLE_BASE/diag, with the directories for each instance at $ORACLE_HOME/diag/$ORACLE_SID, at the same level as the traditional bdump, udump and cdump directories and the initialization parameters background_dump_dest and user_dump_dest are deprecated in 11g.

You can use the new initialization parameter diagnostic_dest to specify an alternative location for the diag directory contents.

In 11g, each $ORACLE_HOME/diag/$ORACLE_SID directory may contain these new directories:

*

alert - A new alert directory for the plain text and XML versions of the alert log.

*

incident - A new directory for the incident packaging software.

*

incpkg - A directory for packaging an incident into a bundle.

*

trace - A replacement for the ancient background dump (bdump) and user dump (udump) destinations.

*

cdump - The old core dump directory retains it's 10g name.

Let's see how the 11g alert log has changed.

Alert log changes in 11g

Oracle now writes two alert logs, the traditional alert log in plain text plus a new XML formatted alert.log which is named as log.xml.

"Prior to Oracle 11g, the alert log resided in $ORACLE_HOME/admin/$ORACLE_SID/bdump directory, but it now resides in the $ORACLE_BASE/diag/$ORACLE_SID directory".

Fortunately, you can re-set it to the 10g and previous location by specifying the BDUMP location for the diagnostic_dest parameter.

But best of all, you no longer require server access to see your alert log since it is now accessible via standard SQL using the new v$diag_info view:

select name, value from v$diag_info;

For complete details, see MetaLink Note:438148.1 - "Finding alert.log file in 11g".

regards,

rajeshkumar g