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.
Next, we use SQL*Net client tracing facility and find out where the IP alias resolution happens for addresses in case of connections redirected by a listener to a remote instance — it’s on the client side! Finally, we see how to fix intermittent ORA-12545 errors and understand why Oracle keeps insisting on adding VIP aliases in your DNS and also find out the reliable method of avoiding IP aliases resolution all together by changing server-side listener configuration to use numeric IP addresses instead of VIP aliases.
Well, that was the summary so enjoy the video itself. You probably want to go to Youtube directly to view it in HD – embedded size is not ideal.
I’ll be in Canberra next week presenting at the ACT Oracle User Group Developer and DBA Seminar Day on Thursday, 23 July 2009. If you are in Australian capital city, I’d be very much looking forward to see you there!
The topic I will be presenting is 11g New Features Out of the Box. I presented it few times already but originally, it’s based on Christo Kutrovsky’s presentation from Oracle Open World 2007. Unlike many presentations on 11g new features, this session will be focused on the enhancements that often go unnoticed and not marketed widely but boost DBA productivity and are available out of the box without much implementations efforts.
I’m most likely coming in Canberra the day before and will do some sightseeing with my family so all suggestions are welcome. That reminds me… Need to book the hotel!
When: Friday, July 17, 2009 5:30 PM (please, make sure to RSVP yes/no/maybe)
Where:Sydney CBDJoin meetup for the detailed location.
The topic for this meetup is quite exciting - Oracle Exadata and everything about it. David Centellas, Senior Database Consultant from Oracle will do technical presentation on Exadata and, after the break, we will have a open forum discussion where two Oracle’s Enterprise Architects, Tim Rubin and Chris Jones, will answer our questions and share thir real-world experience.
It’s amazing how many companies still follow a mainly “perimeter security” approach when it comes to controlling access to sensitive information—their focus is on network security using firewalls, advanced authentication options, and so on. Even with such measures, it’s very common to setup strong barriers to the outside world but very little by way of internal limits; most internal people have some level of access to servers that store and process sensitive data.
Well, there’s nothing wrong with pre-screening your stuff, or having access to the sensitive information, or setting up advanced authentication. Nevertheless, we at Pythian always hear this argument: “Our environment is much more secure if only exposed to a very limited number of people.” If, however, security stops here, this is a very shortsighted position.
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