[Linux-cluster] Starter Cluster / GFS

Jonathan Barber jonathan.barber at gmail.com
Thu Nov 11 13:25:38 UTC 2010

On 11 November 2010 10:46, Gordan Bobic <gordan at bobich.net> wrote:
> Jankowski, Chris wrote:
>> Gordan,
>> I did not ask for bonding.  This should work.  I asked for
>> multiple independent links - different networking interfaces
>> configured for different IP subnets mapping to different VLANS.
>> STP is, these days, run on a per VLAN basis. Having multiple
>> links in different VLANs protects against important classes of
>> network failures.  Bonded interface does not do it. This must
>> be integrated in the clustering software.
> I don't quite see the point you're making. If your goal is redundant
> networking, then you can achieve that by having bonded interfaces in each
> node, and each of the components of the bonded interface should go to a
> different switch. That will give you both extra bandwidth and a redundant
> path between all the nodes, which will ensure you don't end up with a
> partitioned cluster.

Chris' point is that if the STP has to recalculate (for example if the
STP root node dies), then having multiple interfaces in the same VLAN
will not help (if the time taken to recalculate is longer than the
fencing timeout). But, if he can run the heartbeat across multiple
VLANs, and the network supports per-VLAN STP, then he lowers the risk
of both VLANs being affected by the same event and therefore reduces
the likelihood of a shootout between the cluster nodes.

Of course, it depends on the topology of the STP domains as to whether
you are guaranteed to maintain at least one path between nodes in the
cluster given a STP node failure.

> Gordan
Jonathan Barber <jonathan.barber at gmail.com>

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