[ClusterLabs] 2-Node Cluster Pointless?

Christine Caulfield ccaulfie at redhat.com
Tue Apr 18 04:08:36 EDT 2017


> 
> This isn't the first time this has come up, so I decided to elaborate on
> this email by writing an article on the topic.
> 
> It's a first-draft so there are likely spelling/grammar mistakes.
> However, the body is done.
> 
> https://www.alteeve.com/w/The_2-Node_Myth
> 

An excellent article. One small point I noticed though. "Fabric Fencing"
more usually refers to SCSI reservation fencing (hence it does not
isolate the node from the cluster, just shared storage) - often  over
Fibre-channel (hence "fabric") though I believe iSCSI supports it too.

While this doesn't take the node out of the cluster it does prevent
damage to shared storage and allows non-clustered applications to
continue working if it's just the cluster network interconnect that has
failed.

IMO SCSI fencing should never be used on a 2 node cluster for reasons
you have already described very clearly.

Chrissie




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