Enabling cluster failover in a DAFS configuration

Designating failover addresses in etc/hosts

Failover paths in the etc/hosts file

The /etc/hosts file lists the following information for failover paths:

IP addresses of the VI NICs on each filer
The failover host names and addresses for each filer

Failover names for VI NICs

In the /etc/hosts file, the -failover designation is included in the host name of a VI NIC to indicate that it is a failover path.

Example

filerA-failover-viip0

Sample etc/hosts file

The following example shows the client's /etc/hosts entries for the configuration shown in Configuration example.

# VIP_ADDRESS

192.168.0.1 filerA-viip0

192.168.1.1 filerA-viip1

192.168.0.3 filerB-viip0

192.168.1.3 filerB-viip1

# Failover addresses

192.168.0.3 filerA-failover-viip0

192.168.1.3 filerA-failover-viip1

192.168.0.1 filerB-failover-viip0

192.168.1.1 filerB-failover-viip1

Explanation of sample /etc/hosts file

The # VIP_ADDRESS entries list the local IP addresses and symbolic names of the VI NICs installed on each filer in the clustered pair. The # Failover addresses entries list the failover address for each local VIP_ADDRESS.

In this sample /etc/hosts file, each NIC IP address corresponds to a local host name and a failover host name. For example, the NIC IP address 192.168.0.1 on filer A has the following host names:

filerA-viip0 -- The local NIC host name.
filerB-failover-viip0 -- A failover NIC host name that indicates that Filer A is the takeover filer when Filer B fails.

How the client identifies the failover path

If Filer A fails, the client performs a lookup for a host name with the failover designator. The lookup returns the following addresses:

192.168.0.3 filerA-failover-viip0
192.168.1.3 filerA-failover-viip1

These addresses correspond to the following NICs on filerB:

filerB-viip0
filerB-viip1

Editing the etc/hosts file

To edit the /etc/hosts file, complete the following steps.

Step	Action
1	Use a text editor such as `vi` to open the client's /etc/hosts file. Example # cd /etc # vi hosts
2	For each VI NIC, add a line with the following format: ip_address hostname-viipN ip_address is the IP address of the VI NIC. hostname is the filer's local host name. `viip` is VI over IP. N is the number of the NIC (0, 1, 2, 3). Example 192.168.0.1 filerA-viip0
3	Add lines with the following format to designate the failover addresses: ip_address hostname-failover-viipN ip_address is the IP address of the VI NIC. hostname-`failover-viipN` is the symbolic name of the failover VI NIC plus the failover designator. hostname is the filer's host name. `viip` is VI over IP. N is the number of the NIC (0, 1, 2, 3). Example `1` 92.168.0.3 filerA-failover-viip0

Step

Action

Use a text editor such as vi to open the client's /etc/hosts file.

Example

# cd /etc

# vi hosts

For each VI NIC, add a line with the following format:

ip_address hostname-viipN

ip_address is the IP address of the VI NIC.

hostname is the filer's local host name.

viip is VI over IP.

N is the number of the NIC (0, 1, 2, 3).

Example

192.168.0.1 filerA-viip0

Add lines with the following format to designate the failover addresses:

ip_address hostname-failover-viipN

ip_address is the IP address of the VI NIC.

hostname-failover-viipN is the symbolic name of the failover VI NIC plus the failover designator.

hostname is the filer's host name.
viip is VI over IP.
N is the number of the NIC (0, 1, 2, 3).

Example

1 92.168.0.3 filerA-failover-viip0