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

[Steven Dake]

On 07/02/2012 08:19 AM, Andrew Martin wrote:
> Hi Steve,
> 
> Thanks for the clarification. Am I correct in understanding that in a
> complete network, corosync will automatically re-add nodes that drop out
> and reappear for any reason (e.g. maintenance, network connectivity
> loss, STONITH, etc)?
> 

Apologies for delay - was on PTO.

That is correct.

Regards
-steve

> Thanks,
> 
> Andrew
> 
> ------------------------------------------------------------------------
> *From: *"Steven Dake" <sdake at redhat.com>
> *To: *"The Pacemaker cluster resource manager"
> <pacemaker at oss.clusterlabs.org>
> *Cc: *discuss at corosync.org
> *Sent: *Friday, June 29, 2012 9:40:43 AM
> *Subject: *Re: [Pacemaker] Different Corosync Rings for Different Nodes
> in Same Cluster?
> 
> On 06/29/2012 01:42 AM, Dan Frincu wrote:
>> Hi,
>>
>> On Thu, Jun 28, 2012 at 6:13 PM, Andrew Martin <amartin at xes-inc.com>
> wrote:
>>> 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?
>>
>> Added corosync ML in CC as I think this is better asked here as well.
>>
>> Regards,
>> Dan
>>
>>>
>>> Thanks,
>>>
>>> Andrew
>>>
>>> ________________________________
>>> 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?
>>>
> 
> In general I think you cannot do what you describe.  Let me repeat it so
> its clear:
> 
> A B C - NET #1
> A B   - Net #2
> 
> Where A, B are your cluster nodes, and C is your quorum node.
> 
> You want Net #1 and Net #2 to serve as redundant rings.  Since C is
> missing, Net #2 will automatically be detected as faulty.
> 
> The part about corosync automatically repairing nodes is correct, that
> would work (If you had a complete network).
> 
> Regards
> -steve
> 
>>> 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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>>>>
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>>>> Bugs: http://bugs.clusterlabs.org
>>>>
>>>
>>>
>>>
>>> --
>>> Dan Frincu
>>> CCNA, RHCE
>>>
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>>>
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>>>
>>>
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>>>
>>
>>
>>
> 
> 
> 
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> 
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