[Pacemaker] Two resource nodes + one quorum node

[Arvydas]

i wonder what is the mechanics behind fence looping? Could anyone explain it 
in detail.

Since in master/slave scenario, slave shoots master and becomes master, why 
would shot-down-node shoot new-master when it is back? i only see it like 
this: a shot-down-node comes back and can't see the state of new master, but 
it would take some really nasty glich in networking or some bug, since we 
can specify two rings for example, so only way to not see the state of other 
node is not able to ping internet at all, thus not able to shoot anything


sincerely,
arvydas
----- Original Message ----- 
From: "Lars Marowsky-Bree" <lmb at suse.com>
To: "The Pacemaker cluster resource manager" <pacemaker at oss.clusterlabs.org>
Cc: "Michael Schwartzkopff" <misch at clusterbau.com>
Sent: Thursday, June 13, 2013 12:33 PM
Subject: Re: [Pacemaker] Two resource nodes + one quorum node


On 2013-06-13T07:45:09, Andrew Beekhof <andrew at beekhof.net> wrote:

> Its certainly possible to build a decent 2-node cluster, but there are 
> several non-obvious steps that are required - preventing fencing loops 
> being one.

Given that 2-node clusters are probably still the 90%+ majority, I
wonder if we shouldn't make them easier somehow.

One of the caveats is that no-quorum-policy defaults to a value that
doesn't make sense for <=2 nodes; maybe we should change that again?

And maybe we can add generic code to pacemaker/corosync to avoid fence
loops: don't start automatically after an unclean restart, generic delay
of the not-yet-DC node if a 2-node cluster splits, etc.

What other caveats are there?


Regards,
    Lars

-- 
Architect Storage/HA
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, 
HRB 21284 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde


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