[Linux-cluster] Why Redhat replace quorum partition/lock lun with new fencing mechanisms?

[jOe]

On 6/16/06, Kevin Anderson <kanderso at redhat.com> wrote:
>
> On Fri, 2006-06-16 at 00:30 +0800, jOe wrote:
>
>
> >
> > Thank you very much Kevin, your information is very useful to us and
> > i've shared it to our engineer team.
> > Here are two questions still left:
> > Q1: In a two node cluster config, how does RHCS(v4) handle the
> > heartbeat failed ? (suppose the bonded heartbeat path still failed by
> > some bad situations).
>
> Current configuration requires using power fencing when running the
> special case two node cluster.  If you lose heartbeat between the two
> machines, both nodes will attempt to fence the other node.  The node
> that wins the fencing race gets to stay up, the other node is reset and
> won't be able to re-establish quorum until connectivity is restored.
>
> > When using quorum disk/lock lun, the quorum will act as a tier breaker
> > and solve the brain-split if heartbeat failed. Currently the GFS will
> > do this ? or other part of RHCS?
>
> Quorum support is integrated in the core cluster infrastructure so is
> usable with just RHCS.  You do not need GFS to use a quorum disk.
>
> >
> > Q2: As you mentioned the quorum disk support is added into  RHCS v4.4
> > update release, so in a two-nodes-cluster config "quorum disk+bonding
> > heartbeat+fencing(powerswitch or iLO/DRAC) (no GFS)" is the
> > recommended config from RedHat? Almost 80% cluster requests from our
> > customers are around two-nodes-cluster(10% is RAC and the left is hpc
> > cluster), We really want to provide our customers a simple and solid
> > cluster config in their production environment, Most customer
> > configure their HA cluster as Active/passive so GFS is not necessary
> > to them and they even don't want GFS exists in their two-nodes-cluster
> > system.
>
> If you have access to shared storage, then a two node cluster with
> quorum disk/fencing would be a better configuration and could be the
> recommended configuration.  However, there are still cases where you
> could have a two node cluster with no shared storage.  Depends on how
> the application is sharing state or accessing data.  But for an
> active/passive two node failover cluster, I can see where the quorum
> disk will be very popular.
>
> Kevin
>
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Thank you very much.

Jun
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