26 October 2012

Learning to Love the ADR - Part 1: Location, Location, Location!

This post is the first in a short series about Oracle 11g ADR. These posts are based on the presentations I gave at the NoCOUG Summer Conference in August 2011 and at the RMOUG Training Days in February 2012.

The Automatic Diagnostic Repository, or "ADR", is a location on disk where an Oracle instance keeps many files of diagnostic data that tools like Enterprise Manager or ADR Command Interpreter (adrci) use for gathering and presenting information to the user. When we refer to diagnostic files, we are talking about:
  • Alert logs (RDBMS instance, ASM instance, Listener)
  • Trace files (e.g. 10046 or 10053 as well as system-generated)
  • Core dumps
Now in prior versions of Oracle, you would expect to find these files under $ORACLE_BASE/admin/$ORACLE_SID in bdump, cdump or udump, by default. You could always specify different locations with the %_DUMP_DEST initialization parameters, of course. The log files would grow ad infinitum if not properly rotated, compressed, archived and/or truncated, possibly causing some headaches with disk space management.

As of Oracle 11g, however, much (but not all) of this is managed by the instance now. As an added bonus, Oracle moved the locations of these files, as I'm sure many of you with alert log monitoring software have found out by now. The thing that catches most DBAs off-guard when upgrading to 11g is the change in location for these files, especially the alert log.