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Re: [Linux-cluster] Repeated fencing



Hi Doug, 

the split brain is what is happening to you ;-)

From wikipedia: http://en.wikipedia.org/wiki/High-availability_cluster
"HA clusters usually use a heartbeat private network connection which is used to monitor the health and status of each node in the cluster. One subtle, but serious condition every clustering software must be able to handle is split-brain. Split-brain occurs when all of the private links go down simultaneously, but the cluster nodes are still running. If that happens, each node in the cluster may mistakenly decide that every other node has gone down and attempt to start services that other nodes are still running. Having duplicate instances of services may cause data corruption on the shared storage."

The qourum disk is a good choice to avoid it as they have told you.

Good luck, 

Greetings, 

ESG



2010/2/23 Doug Tucker <tuckerd lyle smu edu>
> Hi Doug, maybe you can avoid this kind of problem using a quorumdisk partition. a two node cluster is split-brain prone and with a quorumdisk partition you can avoid split-brain situations, which probably is causing this behavior.
>
> So, about use a cross-over (or straight) cable, I don't know any issue about it, but, try to check if it's using full-duplex mode. half-duplex mode on cross-over linked machines probably will cause heartbeat problems.
>
> cya..

Can you give me a little info about "split-brain" issues?  I don't
understand what you mean by that, and what I'm solving with a
quorumdisk.  And it has always worked fine, it just started happening
after the install of this newer kernel/gfs module.  The other 2 node
cluster is still rock solid.  Also, the network interfaces on the
crossover are full duplex.  Thanks for writing back, you're the first
person who offered anything.


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