Cluster subnet?

[MACscr]

I want cluster communication to happen on its own subnet, but storage/web, etc, on another. How do accomplish this with proxmox? Do i simply manually edit the hostnames in the cluster.conf atfter install with ones that simply point to the particular subnet ip's? Thats the only solution I can think of so far and im not 100% sure how friendly proxmox would be to it.

 

[dietmar]

The cluster stack resolves the hostname with /etc/hosts to get the IP address.

 

[MACscr]

Right, but wont other communication to the proxmox hostnames go through the cluster subnet if i change all the servers hostname records in the hosts file to reflect that particular subnet? I obviously dont want any file transfers, migrations, etc, to go over that subnet since multicast with cman is super sensitive to network bw. Is it save for me to simply just edit the cluster.conf manually to whatever hostnames i want? aka, host1.cluster, host2.cluster, etc?

 

[dietmar]

Right, but wont other communication to the proxmox hostnames go through the cluster subnet if i change all the servers hostname records in the hosts file to reflect that particular subnet?

yes, migration also use this subnet.

I obviously dont want any file transfers, migrations, etc, to go over that subnet since multicast with cman is super sensitive to network bw.

I never saw problems with that.

Is it save for me to simply just edit the cluster.conf manually to whatever hostnames i want? aka, host1.cluster, host2.cluster, etc?

No, please do not change the names there.

 

[MACscr]

Well you will find that pretty much all Redhat staff members disagree with you and clearly state that cluster communication needs to be on its own interface. The fact that you have been lucky not to experience issues is irrelevant to what its recommended by the people that make the clustering components. Its like saying you have been running raid 0 for years without issues, so it should be fine in production. If a cluster has communication issues and fencing is involved, you can be in a huge world of hurt.

What would be the problem with changing the hostnames in the cluster.conf? I mean, it has to be customized anyway for the fencing information, right?

 

[dietmar]

Well you will find that pretty much all Redhat staff members disagree with you and clearly state that cluster communication needs to be on its own interface.
The fact that you have been lucky not to experience issues is irrelevant to what its recommended by the people that make the clustering components. Its like saying you have been running raid 0 for years without issues, so it should be fine in production. If a cluster has communication issues and fencing is involved, you can be in a huge world of hurt.

We also recommend to use a separate network for cluster, and do not run any storage or VM related traffic over this network. But traffic from VM migration is not really a problem.

What would be the problem with changing the hostnames in the cluster.conf? I mean, it has to be customized anyway for the fencing information, right?

The name is used to identify nodes (no, there is no need to change names for fencing).