*.remote_listener – Um, ok, we didn’t expect that – REMOTE_LISTENER - part #1
From time to time even us seasoned DBA’s run into a feature, behavior or trick we didn’t know existed. This is really interesting and worthy of sharing in the hopes that someone else can learn something they didn’t previously know.
Recently while implementing an new Oracle Database Appliance, X8-2M (ODA) for a Re-Quest Managed Services customer, we restored a database on the PROD ODA using a backup from the existing PROD system created several weeks prior. The source system was an Oracle RAC system on Windows and obviously the ODA is Linux (and in this case no longer utilizing RAC). Since we want the new PROD DB’s init.ora parameters to match the current production system we used the same parameter file. Seems harmless enough, right? Not so much since one of the entries in that init.ora was:
*.remote_listener='❮hostname❯:1521'
This is where it got weird. When the ODA DB was restored it notified the Windows RAC cluster (the current PROD system) that this DB was created and availabe. The Windows RAC system said “ok cool, I’ll start sending you occasional traffic”. Since this was a cloned database and was opened, suddenly the Windows RAC system started sending 1/3 of its traffic to this newly created database. As soon as that started, we began receiving alerts from Oracle Enterprise Manager indicating that the Windows RAC was no longer responding. Our immediate response was to shut down the ODA database. At that point the Window RAC said “oh ok, bye, I won’t send you anymore traffic. Good luck to you”. That’s when things returned to normal for the end users.
The lesson learned is to always ensure that the remote_listener parameter must always either be removed or at a minimum updated. But the interesting part to this author is that Oracle RAC allowed a Linux DB to join the already existing two node Windows RAC system. Since these are different endian’s I didn’t think that was even possible. I can understand why the Linux system tried to connect to Windows, but it shocked me that Window’s actually allowed it and began sending it traffic.
**Author – Re-Quest-EC