[Pacemaker] Different Corosync Rings for Different Nodes in Same Cluster?

[Andrew Martin]

Hi Dan, 


Thanks for the help. If I configure the network as I described - ring 0 as the network all 3 nodes are on, ring 1 as the network only 2 of the nodes are on, and using "passive" - and the ring 0 network goes down, corosync will start using ring 1. Does this mean that the quorum node will appear to be offline to the cluster? Will the cluster attempt to STONITH it? Once the ring 0 network is available again, will corosync transition back to using it as the communication ring, or will it continue to use ring 1 until it fails? 


The ideal behavior would be when ring 0 fails it then communicates over ring 1, but keeps periodically checking to see if ring 0 is working again. Once it is, it returns to using ring 0. Is this possible? 


Thanks, 


Andrew 

----- Original Message -----

From: "Dan Frincu" <df.cluster at gmail.com> 
To: "The Pacemaker cluster resource manager" <pacemaker at oss.clusterlabs.org> 
Sent: Wednesday, June 27, 2012 3:42:42 AM 
Subject: Re: [Pacemaker] Different Corosync Rings for Different Nodes in Same Cluster? 

Hi, 

On Tue, Jun 26, 2012 at 9:53 PM, Andrew Martin <amartin at xes-inc.com> wrote: 
> Hello, 
> 
> I am setting up a 3 node cluster with Corosync + Pacemaker on Ubuntu 12.04 
> server. Two of the nodes are "real" nodes, while the 3rd is in standby mode 
> as a quorum node. The two "real" nodes each have two NICs, one that is 
> connected to a shared LAN and the other that is directly connected between 
> the two nodes (for DRBD replication). The quorum node is only connected to 
> the shared LAN. I would like to have multiple Corosync rings for redundancy, 
> however I do not know if this would cause problems for the quorum node. Is 
> it possible for me to configure the shared LAN as ring 0 (which all 3 nodes 
> are connected to) and set the rrp_mode to passive so that it will use ring 0 
> unless there is a failure, but to also configure the direct link between the 
> two "real" nodes as ring 1? 

Short answer, yes. 

Longer answer. I have a setup with two nodes with two interfaces, one 
is connected via a switch to the other node and one is a back-to-back 
link for DRBD replication. In Corosync I have two rings, one that goes 
via the switch and one via the back-to-back link (rrp_mode: active). 
With rrp_mode: passive it should work the way you mentioned. 

HTH, 
Dan 

> 
> Thanks, 
> 
> Andrew 
> 
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-- 
Dan Frincu 
CCNA, RHCE 

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