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Re: [Linux-cluster] Starter Cluster / GFS

On 10-11-11 10:25 PM, Jankowski, Chris wrote:
> Digimer,
> I think you do not make distinction between the network that maintains the hearbeat and the networks to use for fence devices. I'll explain this again.

Perhaps. In my clusters, I use at least three interfaces on three
separate subnets... I put IPMI on one and NA on the second.

> These are two very different things and operated for different purpose.
> The hearbeat network is between the nodes for the purpose of maintaining cluster membership.
> The connections from the nodes to your fence devices form the other two networks.
> In fact speaking of networks in this case is a little limiting. Each of the IP addresses involved may, in principle, be in different IP subnet
> In the example that you gave, you have two (possibly different) networks for fence devices, as you have two fence devices.

You can use the <altname ...> element to define a second totem ring
(redundant ring protocol) to act as a backup, on a second subnet, for
backup cluster communication.

> However, your cluster membership is maintained through the single hearbeat network implicitly defined through the names of the cluster nodes.  I want to have two, independently configurable network like this and heartbeat being sent through both of them. I cannot do this at the moment, as the software will always maintain the hertbeat through the single IP address to which the node name resolves. In your case the heartbeat traffic will always go between an-node01.alteeve.com and an-node02.alteeve.com.
> What I want is to have hertbeat traffic going between:
> an-node01h1.alteeve.com and an-node02h1.alteeve.com
> and between
> an-node01h2.alteeve.com and an-node02h2.alteeve.com
> Whereas my application would access the cluster through:
> an-node01.alteeve.com and an-node02.alteeve.com
> So I would need minimum of 3 Ethernet interfaces per server and minimum of 6 if all links will be bonded, but this is OK. 

Exactly what I do, though RRP is currently limited to two interfaces due
to inherent complexities preventing going beyond that. There is work on
a newly-announced project that will allow for n-number of paths, but
that's alpha stage at this point.

> Regards,
> Chris Jankowski


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