To build an Oracle 12C RAC database – on Virtual Boxes – there’s at least shared storage needed for ASM, and a DNS-server for the SCAN-addresses. Several methods can be used for this, but for the storage in my private project I chose Openfiler, an open source management storage tool, on a separate Virtual Box. It’s like a SAN in real life (the complete system will be three Virtual Boxes: two RAC-nodes and 1 storage Virtual Box). Version Openfiler: 2.99.
O.k. storage is clear, but what about DNS? The quickest and dirtiest way to accomplish this is to use Dnsmasq on every RAC-node. A nice blogpost about this subject is here to be found.
But what I want is a separate DNS-server, just as in real life. The perfect candidate is to use the separate Openfiler Virtual Box. Agreed, a bit more complicated to setup, but I just have to do it once…. I used a nice blogpost about DHCP and DNS setup in the past as my starting point. In this post I will describe the various steps to take to get your own DNS-server on Openfiler, with the complete content of the files I used. The installation of openfiler will be described in another post. So the assumption here is that the openfiler-virtual box is running and accessible.
First the DNS-package has to be installed on Openfiler (internet access needed):
For the RAC-nodes I needed the ip-range 192.168.188.xxx as public, and 192.168.190.xxx as private addresses.
Just a few files to be configured to accomplish this:
– /etc/named.conf which point to the other files:
|—> /srv/named/data/<domain-name-host-file> , in this case srv/named/data/amis.nl.hosts.
|—> /srv/named/data/<reversed-files>
Hereby the content of these files.
/etc/named.conf:
//
// named.conf for Red Hat caching-nameserver
//
options {
directory "/srv/named/data";
dump-file "/srv/named/data/cache_dump.db";
statistics-file "/srv/named/data/named_stats.txt";
/*
* If there is a firewall between you and nameservers you want
* to talk to, you might need to uncomment the query-source
* directive below. Previous versions of BIND always asked
* questions using port 53, but BIND 8.1 uses an unprivileged
* port by default.
*/
// query-source address * port 53;
};
// a caching only nameserver config
//
controls {
inet 127.0.0.1 allow { localhost; } keys { rndckey; };
};
zone "amis.nl" {
type master;
file "amis.nl.hosts";
};
# reverse zone
zone "188.168.192.in-addr.arpa" {
type master;
file "188.168.192.rev";
};
zone "190.168.192.in-addr.arpa" {
type master;
file "190.168.192.rev";
};
include "/etc/rndc.key";
/srv/named/data/<domain-name-host-file> , in my case amis.nl.hosts.
$TTL 86400 ; 1 day @ IN SOA Openfiler2.amis.nl. foo.bar.tld. ( 200612069 ; serial 7200 ; refresh (2 hours) 300 ; retry (5 minutes) 604800 ; expire (1 week) 60 ; minimum (1 minute) ) @ IN NS Openfiler2.amis.nl. Openfiler2.amis.nl. IN A 192.168.188.195 rac1-ol6-121.amis.nl. IN A 192.168.188.100 rac2-ol6-121.amis.nl. IN A 192.168.188.110 rac1-ol6-121-vip.amis.nl. IN A 192.168.188.150 rac2-ol6-121-vip.amis.nl. IN A 192.168.188.160 ol6-121-scan.amis.nl. IN A 192.168.188.210 ol6-121-scan.amis.nl. IN A 192.168.188.220 ol6-121-scan.amis.nl. IN A 192.168.188.230 rac1-ol6-121-priv.amis.nl. IN A 192.168.190.200 rac2-ol6-121-priv.amis.nl. IN A 192.168.190.250
Then the two ‘reversed’ files, named in /etc/named.conf:
First the 188.168.192.in-addr.arpa file:
@ IN SOA Openfiler2.amis.nl admin.amis.nl. ( 200612069 ; serial 7200 ; refresh (2 hours) 300 ; retry (5 minutes) 604800 ; expire (1 week) 60 ; minimum (1 minute) ) 188.168.192.in-addr.arpa. IN NS Openfiler2.amis.nl. 195 PTR Openfiler2.amis.nl. 100 PTR rac1-ol6-121.amis.nl. 110 PTR rac2-ol6-121.amis.nl. 150 PTR rac1-ol6-121-vip.amis.nl. 160 PTR rac2-ol6-121-vip.amis.nl. 210 PTR ol6-121-scan.amis.nl. 220 PTR ol6-121-scan.amis.nl. 230 PTR ol6-121-scan.amis.nl.
Then the 190.168.192.in-addr.arpa file:
$TTL 86400 ; 1 day @ IN SOA Openfiler2. admin.amis.nl. ( 200612069 ; serial 7200 ; refresh (2 hours) 300 ; retry (5 minutes) 604800 ; expire (1 week) 60 ; minimum (1 minute) ) 190.168.192.in-addr.arpa. IN NS Openfiler2.amis.nl. 200 PTR rac1-ol6-121-priv.amis.nl. 250 PTR rac2-ol6-121-priv.amis.nl.
Start the named server:
# service named start
Should give o.k.
You may experience an error while stopping the service:
You may ignore this error for the purpose of this blog. I did..
Make sure the nameserver is started at boottime:
# chkconfig named on
# chkconfig named –list
But is it working? To check this out, you’ll have to reconfigure your DNS-resolving on your own server. In my case the first node of my cluster: ‘rac1-ol6-121’.
To make sure that all the hostnames can be resolved the file /etc/resolv.conf must be edited. Create this file with the following entries:
search amis.nl nameserver 192.168.188.195
But you may experience that this will gets overwritten in OEL6. To overcome this you’ll have to edit the adapter-settings (eth0 / eth1) through the GUI. Or, as Rob state in his blog, create the file /etc/dhclient-enter-hooks with the following content:
make_resolv_conf() {echo "doing nothing to resolv.conf}
So let’s test this (configured this in another domain, jobacle.nl, so the output of the ‘nslookup’ is somewhat different than the configuration above 
):
Openfiler-server (192.168.188.195) is default listening on port 53.
Sources:
Configuring DHCP and DNS on Openfiler 2.3: http://www.denbraber.org/?p=4
RAC-scan dns server setup: http://ora12c.blogspot.nl/2012/08/oracle-rac-scan-dns-server-setup.html
Using Dnsmasq: http://dbaora.com/configure-scan-dns-for-rac-11g-rac-12c-using-dnsmasq-in-oel5-oel6-2/
