[Linux-cluster] IP Resource behavior with Red Hat Cluster

[Jakov Sosic]

On 12/24/2010 05:46 PM, Parvez Shaikh wrote:
> Hi Jakov
> 
> Thank you for your response. My two hosts have multiple network
> interfaces or ethernet cards. I understood from your email, that the
> IP corresponding to "cluster node name" for both hosts, should be in
> the same subnet before a cluster could bring virtual IP up.

No... you misunderstood me. I meant that if the virtual address is
192.168.25.X, than you have to have interface on each node that is set
up with the ip address from the same subnet. That interface does not
need to correspond to the cluster node name. For example:

node1 - eth0 - 192.168.1.11 (netmask 255.255.255.0)
node2 - eth0 - 192.168.1.12 (netmask 255.255.255.0)

IP resource - 192.168.25.100


Now, how do you expect the cluster to know what to do with IP resource?
On which interface can cluster glue 192.168.25.100? eth0? But why eth0?
And what is the netmask? What about routes?

So, you need to have for example eth1 on both machines set up in the
same subnet, so that cluster can glue IP address from IP resource to
that exact interface (which is set up statically). So you also have to
have for example:

node1 - eth1 - 192.168.25.47 (netmask 255.255.255.0)
node2 - eth1 - 192.168.25.48 (netmask 255.255.255.0)

Now, rgmanager will know where to activate IP resource, because
192.168.25.100 belongs to 192.168.25.0/24 subnet, which is active on
node1/eth1 and node2/eth2.

If you were to have another IP resource, for example 192.168.240.44, you
would need another interface with another set of static ip addresses on
every host you intend to run IP resource on...


I hope you get it correctly now.





-- 
Jakov Sosic
www.srce.hr