Welcome back to our videocasts — this is the last video in the series about Oracle RAC Virtual IP’s. I strongly suggest to watch the two previous videos:
I’m writing this post sitting in Vancouver airport but I won’t get into details of my travel complications here, I think it deserves a separate post as it makes a good point for DR plans. :)
What we are looking at during this videocast is how to troubleshoot the connectivity issues that can be caused by VIP’s in Oracle RAC environment and how to diagnose cryptic Oracle error messages using SQL*Net tracing facility on the client side.
We first look at the typical error message “ORA-12545: Connect failed because target host or object does not exist” and how it leads to the IP alias resolution problem that, at first, seems to be easily fixed by changing IP aliases in the connection descriptor to the numerical IP addresses. Then we find out that it’s not enough with Oracle RAC and server-side connection load balancing can still cause you some grief. Read the rest of this entry . . .
The first videocast was quite popular — it has more than 300 views in couple weeks and considering no Hollywood stars were starring in that video and there were no nude scenes, I think it’s fair to say that this format was very much welcomed by the audience.
Today, I’m posting the follow up session on VIP’s (Virtual IP’s) with Oracle RAC. What I demonstrate today is a typical configuration mistake for a RAC databases created with Database Configuration Assistant (DBCA) and what’s the result of such omission.
It’s actually logged as a bug 4338578 on Metalink (thanks to Marcin Przepiorowski for reference). However, I believe it’s not a database issue but (1) misunderstanding how remote listener registration works, (2) documentation bug and (3) DBCA bug.
The init.ora parameter remote_listener defines the list of remote listeners that an instance should register with. The parameter local_listener sets the address for the local listener registration and if not specified, by default it’s hostname and the default port 1521. However, it turns out that the local_listener parameter is used not only for local registration but for something else as well… Read the rest of this entry . . .
“Seeing it once is better than hearing about it a thousand times” — I think this is the closest translation from one Russian proverb. I may add that hearing and seeing might be often better then reading so let me try to start a series of small videocasts about Oracle database technology.
One of the topics that beginners RAC DBA’s (along with network engineers supporting Oracle database infrastructure) are confused about is the Virtual IP usage in Oracle RAC starting from Oracle Clusterware 10g.
With this videocast, I will try to clarify those concerns once and for all. I have embedded the video here in a smaller window so you might want to go directly to YouTube for the full-size version of “Pythian Video: Oracle RAC – Why VIPs“.
This is an experiment for now so let’s see how it goes. Let me know if you find this format useful and don’t forger to rate it on YouTube. Note that if you don’t leave any comments here, I’d never know whether you liked it or not so don’t be shy and comment away…
I would like to share with you the virtual hosts set-up (two nodes each on the application tier, and two on the DB tier) for a customer using 11.5.9.
The Facts
DB Version: 10.2.3
CRS Version: 10.2.0.3
ASM Version: 10.2.0.3
APPS Version: 11.5.9
Set-ups by Sys-Admins
Sysadmins must set up a virtual hostname amongst the two available middle-tier (Applications) hosts. In our case, the hostnames are erpapp01, and erpapp02. Then the sysadmins set up a VIP as erpapp.
We also require from sysadmins virtual hostname amongst the two available backend (database) hosts. Hostnames in our case are erpdb01, and erpdb02. They then set up a VIP as erpdb. Read the rest of this entry . . .
