DNS Config for RAC SCAN… Again…

 

Some time ago I wrote an article about configuring DNS for the SCAN address in Oracle 11gR2 RAC.

Over the last couple of days one of the Oakies has given me some feedback on the article based on his experiences with Oracle Linux 5.

For my virtual RAC installations I typically do the DNS configuration on the host machine, which is running Fedora. It seems Oracle Linux 5 is a little different. Just to make sure I ran through the setup on Oracle Linux 5 and 6 to see what the score was.

Oracle Linux 6 is pretty much the same as Fedora as far as installation and configuration of BIND is concerned. Oracle Linux 5 (and also RHEL5 I assume) is a little funky in that it doesn’t create the default config files automatically. There are sample files you can use, but they contain a load of crap you don’t need and are missing some stuff you do. The easiest way to get it configured is to install the “system-config-bind” package and start the GUI. This notices you have no config and sets it up for you. You can then exit the GUI and do the manual config as described in the article. Very odd.

I’ve made a note about this in the article, so it shouldn’t trip anyone else up. I’ve also given some examples of the manually adjusted default named.conf files for each distro.

Cheers

Tim…

DNS Configuration for SCAN and Editions…

 

A couple of new articles have crept out recently. The first is me pretending to understand DNS.

I used this configuration in place of the “/etc/hosts” in my VMware RAC installation and it worked great.

The second is a brief romp through edition-based redefinition.

This article started to get really big and feel like a rewrite of the manual, so I stripped most of it out and really just left a couple of examples of how it can be used. I figure this is enough to give you a feel for what it can do, but isn’t as daunting as working through the manuals if all you want is a quick taste.

I’ve seen edition-based redefinition described as a killer feature, but I’m not so sure myself. Don’t get me wrong, I think it is really cool, but “really cool” doesn’t always become “frequently used”. As I was playing with it I had flashbacks to Workspace Management introduced in 9i. I’ve spoken to a lot of poeple over the years and very few even remember it exists, let alone use it.

There is nothing conceptually difficult about edition-based redefintion, but there are potentially a lot of working parts involved and therefore a lot of scope for human error and/or confusion. I’m sure some people have been praying for something like this for a long time, and others will remain blissfully ignorant of it forever. It would be interesting to gaze into a crystal ball and see how much this stuff is used in a few years time (and get some lottery results).

Cheers

Tim…