Sun Cluster 2.2 Software Installation Guide

Chapter 12 Installing and Configuring Sun Cluster HA for DNS

This chapter provides instructions for setting up and administering the Sun Cluster HA for DNS data service.

This chapter includes the following sections:

Installing DNS

Sun Cluster HA for DNS is DNS running under the control of Sun Cluster. This section describes the steps to take when installing DNS to enable it to run as the Sun Cluster HA for DNS data service.

How to Install DNS

Refer to your DNS documentation for details about how to set up DNS. Note these differences in a Sun Cluster configuration:

The database is located on the multihost disks rather than on the private disks.
The DNS server is a logical host rather than a physical host.

Decide which logical host is to provide DNS service.

Choose a location on the logical host for the DNS database.

Place the named.conf file and the rest of the files constituting the database here. For example, /logicalhost/dns.

In the /etc/resolv.conf file on all Sun Cluster servers that will be running Sun Cluster HA for DNS, specify the IP address of the logical host providing DNS service.

In the /etc/nsswitch.conf file, add the string dns after files.

Make sure the logical host name for the HA-DNS server is present in the /etc/inet/hosts file on all cluster nodes.

Test DNS outside of the Sun Cluster environment.

For example:

# cd /logicalhost/dns
/usr/sbin/in.named -b /logicalhost/dns/named.conf
# nslookup physicalhost

After you have installed and set up DNS, configure, register, and start Sun Cluster HA for DNS as described in "Installing and Configuring Sun Cluster HA for DNS".

Installing and Configuring Sun Cluster HA for DNS

This section describes the steps used to install, configure, register, and start Sun Cluster HA for DNS. You must install and set up DNS itself and Sun Cluster before performing this procedure.

You will configure Sun Cluster HA for DNS by using the hadsconfig(1M) command. See the hadsconfig(1M) man page for details.

How to Install and Configure Sun Cluster HA for DNS

Once you have installed Sun Cluster and DNS, follow the procedures described in this section to install, configure, register, and activate Sun Cluster HA for DNS.

On each Sun Cluster server, install the SUNWscdns packages in the default location.

If not already installed, use the pkgadd command to install the SUNWscdns package on each Sun Cluster server.

Register the Sun Cluster HA for DNS data service by running the hareg(1M) command on one node.

If you installed Sun Cluster HA for DNS on all potential masters of a logical host but not on all hosts in the cluster, use the -h option to specify the logical host name. Run the hareg(1M) command on only one node.
phys-hahost1# hareg -s -r dns [-h logicalhost]

Run the hadsconfig(1M) command to configure Sun Cluster HA for DNS.

The hadsconfig(1M) command is used to create, edit, and delete instances of a Sun Cluster HA for DNS data service. Refer to "Configuration Parameters", for information on the input you will need to supply to the hadsconfig(1M) command.
phys-hahost1# hadsconfig

Use the hareg(1M) command to enable the Sun Cluster HA for DNS data service and perform a cluster reconfiguration.

Run the hareg(1M) command on only one node.
phys-hahost1# hareg -y dns
The configuration is complete.

Configuration Parameters

This section describes the information you supply to the hadsconfig(1M) command to create configuration files Sun Cluster HA for DNS. The hadsconfig(1M) command uses templates to create these configuration files. The templates contain some default, some hardcoded, and some unspecified parameters. Accept the default values where possible. You must provide values for all parameters that are unspecified.

The fault probe parameters, in particular, can affect the performance of Sun Cluster HA for DNS. Tuning the probe interval value too low (increasing the frequency of fault probes) might encumber system performance, and also might result in false takeovers or attempted restarts when the system is simply slow.

The Sun Cluster HA for DNS data service requires you to set the takeover flag. This flag specifies how Sun Cluster will handle partial failover. There are two options:

y (yes) - Sun Cluster will attempt to switch over the logical host to another master, but if the attempt fails the logical host will remain on the original master.
n (no) - Sun Cluster will not move the logical host to another master, even if it detects problems with the data server, nor will it take any action against the sick data server or database on the logical host.

Note -

The behavior of DNS changes between Solaris 2.6 and Solaris 8. This is because the default bind version differs between these operating environments. This change requires an update to some DNS configuration files. See your DNS documentation for details and instructions.

Configure the Sun Cluster HA for DNS parameters listed in the hadsconfig(1M) input form by supplying options described in Table 12-1.

Table 12-1 Configuration Parameters for Sun Cluster HA for DNS


Parameter	Description
Name of the instance	Nametag used as an identifier for the instance. The log messages generated by Sun Cluster refer to this nametag. The `hadsconfig(1M)` command prefixes the package name to the value you supply here. For example, if you specify "nsdns_119," `hadsconfig(1M)` produces "SUNWscdns_nsdns_119."
Logical host	Name of logical host that provides Sun Cluster HA for DNS service.
Configuration directory	Rooted path name specifying the directory of DNS configuration files and database on multihost disk.
Takeover flag	Specifies whether a failure of this instance will cause a takeover or failover of the logical host associated with the data service instance. Possible values are `y` (yes) and `n` (no).
Time between probes	The interval, in seconds, of the fault probing cycle. Accept the default value of 60 seconds.
Probe timeout	The time, in seconds, after which a fault probe will time out. The default timeout value is 60 seconds.