Infrastructure at your Service

Introduction

Oracle Database Appliance has quite a lot of nice features, but when looking into the documentation, at least one thing is missing. How to configure multiple listeners? Odacli apparently doesn’t know what’s a listener. Let’s find out how to add new ones.

odacli

Everything should be done using odacli on ODA, but unfortunately odacli has no commands for configuring listeners:

odacli -h | grep listener
nothing!

The wrong way to configure a listener

One could tell me that configuring a listener is easy, you just have to describe it into the listener.ora file, for example:

echo "DBI_LSN=(DESCRIPTION_LIST=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=oda-dbi-test)(PORT=1576))))" >> $ORACLE_HOME/network/admin/listener.ora

… and start it with:
lsnrctl start DBI_LSN

But if it works fine, it’s not the best way to do that. Why? Simply because it will not survive a reboot.

A better way to configure a listener: through Grid Intrastructure

ODA makes use of Grid Infrastructure for its default listener on port 1521. The listener is an Oracle service running in Grid Infrastructure, so additional listeners should be declared in the Grid Infrastructure using srvctl. This is an example to configure a new listener on port 1576:

su - grid
which srvctl

/u01/app/19.0.0.0/oracle/bin/srvctl
srvctl add listener -listener DBI_LSN -endpoints 1576
srvctl config listener -listener DBI_LSN

Name: DBI_LSN
Type: Database Listener
Network: 1, Owner: grid
Home:
End points: TCP:1576
Listener is enabled.
Listener is individually enabled on nodes:
Listener is individually disabled on nodes:
srvctl start listener -listener DBI_LSN
ps -ef | grep tnslsn | grep DBI

oracle 71530 1 0 12:41 ? 00:00:00 /u01/app/19.0.0.0/oracle/bin/tnslsnr DBI_LSN -no_crs_notify -inherit

The new listener is running fine, and the listener.ora has been completed with this new item:

cat /u01/app/19.0.0.0/oracle/network/admin/listener.ora | grep DBI
DBI_LSN=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=IPC)(KEY=DBI_LSN)))) # line added by Agent
ENABLE_GLOBAL_DYNAMIC_ENDPOINT_DBI_LSN=ON # line added by Agent
VALID_NODE_CHECKING_REGISTRATION_DBI_LSN=SUBNET # line added by Agent

For sure, configuring a listener on a particular port is only possible if this port is not in use.

Removing a listener

If you want to remove a listener, you just need to remove the service from Grid Infrastructure:
su - grid
srvctl stop listener -listener DBI_LSN
srvctl remove listener -listener DBI_LSN
ps -ef | grep tnslsn | grep DBI

no more listener DBI_LSN running
cat /u01/app/19.0.0.0/oracle/network/admin/listener.ora | grep DBI
no more configuration in the listener.ora file

Obviously, if you plan to remove a listener, please make sure that no database is using it prior removing it.

How to use this listener for my database

Since 12c, a new LREG process in the instance is doing the registration of the database in a listener. Previously, this job was done by PMON process. The default behavior is to register the instance in the standard listener on 1521. If you want to configure your database with the new listener you just created with srvctl, configure the local_listener parameter:

su - oracle
. oraenv <<< DBTEST
sqlplus / as sysdba
alter system set local_listener='(ADDRESS=(PROTOCOL=TCP)(HOST=oda-dbi-test)(PORT=1576))' scope=both;
alter system register;
exit;

No need to reboot anything.

What about standard 1521 listener?

You may think about removing the standard listener on port 1521. But I wouldn’t do that. I think it’s better to keep this default one, even if none of your databases are using it. It could later cause troubles when patching or configuring something else on your ODA.

Conclusion

The listener management with odacli could come one day, but for now (19.9 and before) you still have to configure it using Grid Infrastructure. It’s quite easy and pretty straightforward if you do it the proper way.

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Jérôme Dubar
Jérôme Dubar

Senior Consultant