As many of you already know, Oracle released 11g Release 2 of the database for Linux x86 and x86-64. That is really cool and this time I don’t want to miss out on researching some new features of the new release. I have spent some time reading up about 11.2 and for what it’s worth I’d consider it more of a step forward compared to 11.1 which IMO is just a glorified 10.2.0.4 with a lot of cost options. But I disgress….
The reason of this post is to allow the reader to set up his own DNS server for building an 11.2 RAC system. As you may know, 11.2 uses DNS for two main purposes:
- Grid Plug and Play
- Single Client Access Name (SCAN)
Grid Plug and Play is something I’ll look at later so let’s focus on the SCAN addresses. The documentation states that we should at least provide 3 IP addresses for a single SCAN name which will be used in a round robin fashion (reference: Section 18.104.22.168 IP Address Requirements for Manual Configuration in the Grid Infrastructure Installation Guide for Linux).
Huh? Are the DBAs now tasked with DNS administration? Probably not, but it doesn’t hurt understanding the concepts, especially if you are like me and want a RAC cluster in your lab environment.
DNS and Linux
I initially looked at DNS when still at the University which seems like a long time ago nowadays. Back then Linux was the uni’s preferred non-Windows platform so I knew which package to install. The following example uses bind 9.3.4-6P1.el5 which is the unpatched DNS server distributed with RHEL 5 update 2.
A word of caution: this article shouldn’t be used to set up a production DNS server, it’s merely intended to get you a DNS server for a lab environment!
With all that said, let’s proceed to getting our SCAN addresses registered. First of all, use rpm to install the package.
Once that’s installed, we need to configure our DNS server. bind9 comes with a number of sample configuration files which make our life a little easier. Traditionally, bind is configured in 2 places:
- /etc/named.conf for the zone definition and
- /var/named for the zone configuration.