/etc/oratab entries are deleted after applying October 2017 Release Update

This short blog post will explain a change in the behaviour of how the /etc/oratab file is maintained by the oraagent.bin process in Oracle 12c Release 2 with an installed October 2017 Release Update.

How is the /etc/oratab file maintained?

During the lifetime of an Oracle Cluster, new databases are created or old ones are deleted. Despite the databases created by a user, Oracle creates by default additional instances like +ASMx instances or the -MGMTDB instance for the Grid Infrastructure Management Repository. These instances are added to the /etc/oratab by the oraagent.bin process automatically.

Every entry added by this process is marked with the comment # line added by Agent.

$> vi /etc/oratab
...
+ASM1:/app/grid/product/12.2.0.1:N # line added by Agent
-MGMTDB:/app/grid/product/12.2.0.1:N
TESTDB:/app/oracle/product/12.1.0.2:N # line added by Agent
OWNDB:/app/oracle/product/12.2.0.1:N
NEWDB:/app/oracle/product/12.2.0.1:N # line added by Agent

Of course you can add additional entries too.

Every action performed by the oraagent.bin is logged to a corresponding $ORACLE_BASE/diag/crs/<Hostname>/crs/trace/*_oraagent_*.trc file.

Behaviour Change

After applying the October 2017 Release Update, every /etc/oratab entry belonging to either the Grid Infrastructure 12c Release 2 or to instances running in an Oracle Database 12c Release 2 home are deleted. But only entries which include the comment # line added by Agent are considered for deletion.

Instances beloging to older releases are not deleted, even if the comment line is included in there definitions.

$> vi /etc/oratab
...
-MGMTDB:/app/grid/product/12.2.0.1:N
TESTDB:/app/oracle/product/12.1.0.2:N # line added by Agent 
OWNDB:/app/oracle/product/12.2.0.1:N

The +ASMx instance and the instance for the Oracle 12c Release 2 database are gone.

Avoid Deletion

If you need these entries for your own scripts, you have two possibilies to avoid the automatic deletion.

  1. Remove the comment line before applying the Release Update
  2. Add a new oratab entry without the comment line manually

By the way, before the /etc/oratab file is updated, a backup is created under $ORACLE_HOME/srvm/admin/oratab.bak.<Hostname>. The Oracle Home can be either the Grid Infrastructure or an Oracle Database Home depending on what triggered the update – e.g. the Database Creation Assistant (DBCA).

References

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