[Linux-cluster] Clusters with multihomed hosts

[Flavio Junior]

You can use bonding NICs with active-backup mode.

Only one NIC is used at a time, the second will only come up if the primary
(active) fails.

Dont forget to configure miimon value for link monitor.

--

Flávio do Carmo Júnior aka waKKu

On Thu, Nov 13, 2008 at 2:21 PM, Michael O'Sullivan <
michael.osullivan at auckland.ac.nz> wrote:

> Hi all,
>
> I need to know more about using redundant NICs in clusters.
>
> I have a 2-node cluster with 2 NICs in each node. The first NICs on each
> node are connected to one switch, the second NICs on each node are connected
> to another switch. This is an experimental arrangement so I am using
> /etc/hosts instead of DNS. It appears that the cluster software becomes
> confused if I put both NICs for the hosts in the /etc/hosts file, even if
> they are in different subnets. Here is the /etc/hosts file I would like to
> use:
>
> # localhost line
> 192.168.10.1     node1
> 192.168.10.2     node2
> 192.168.20.1     node1 # Second NIC on node 1
> 192.168.20.2     node2 # Second NIC on node 2
>
> but this seems to cause the cluster to hang (confused about which NIC to
> use?), so I have removed the last 2 lines and everything works fine.
> However, this means if the switch on the 192.168.10.x subnet fails the
> cluster will "break". If the cluster would recognise that node1 and node2
> are available via the second NICs then I wouldn't have to worry about this
> single point-of-failure.
>
> I have thought about bonding the NICs which (I think) would take care of
> the problem, but I have heard that boding two NICs usually does not  give
> double the bandwidth. I  have read a little about high-availability and
> failing over IP addresses, but this seems to be between different nodes, not
> different NICs in the same host.
>
> Would anyone please be able to give me some direction about the best way to
> set up my cluster and NICs to make the cluster reliable in the event of
> switch failure? And keep the full bandwidth of the NICs intact?
>
> Thanks in advance for any help you can give. Kind regards, Mike
>
> --
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>
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