Oracle’s new ADR with command interface shows promise for database administrators who like to script their
own solution for quickly scraping the alert log and automatically looking for errors.
Oracle’s alert log is a chronological log of important messages and errors
that are generated using an Oracle database. Quite often it's the first place
DBAs check to see if there are errors being generated or to see if the Oracle
database is healthy and not spitting out errors and complaining about something.
If you have have never seen an alert log, below is a snippet of some of the
errors (ORA-) and messages that you will find in the alert log. I’ve
included two different snippets. One is a pure text file, and one that is new
to many, an XML alert log. Both are generated but the prior is, as suggested
by Oracle, not being maintained and not receiving the same messaging as the
XML alert log.
From the text alert log:
Wed Dec 09 14:55:16 2009
Errors in file /opt/app/oracle/diag/rdbms/db11/db11/trace/db11_ora_14798.trc:
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/oradata/db11/redo03.log'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
From the XML alert log:
< msg time='2009-12-09T14:55:16.441-07:00' org_id='oracle' comp_id='rdbms'
client_id='' type='UNKNOWN' level='16'
module='sqlplus@ludwig (TNS V1-V3)' pid='14798'>
<txt>Errors in file /opt/app/oracle/diag/rdbms/db11/db11/trace/db11_ora_14798.trc:
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/oradata/db11/redo03.log'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
</txt>
< /msg>
Clearly, these logs are very similar except for the XML tags. These XML tags
cause some interesting problems for those of us that like to scrape the alert
log with system utilities. It isn’t as easy as pointing the scripts
at a new file out on disk. Thankfully Oracle has provided a utility (ADRCI)
that
can be used to extract diagnostic information generated from an Oracle database,
including the alert log.
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