[Gluster-users] HA replica
mikestump at comcast.net
Thu Feb 18 02:25:16 UTC 2016
On Feb 13, 2016, at 6:21 PM, Ravishankar N <ravishankar at redhat.com> wrote:
> Like Bishoy said in another thread, quorum does not really make sense in 2-replica because there is no notion of majority.
Ah, could you update the doc to note that a quorum isn’t formed from all the members of the cluster, but rather from the replicas and arbiters involved in the specific operation? In a 10x3 cluster, it would be formed from just 3 nodes, not 30.
I expected that in a 10 (5x2) server setup, 6 means majority. Any island of 5 or less, would not be a majority. Any island of 6 or more, would form a majority. The doc isn’t clear on the point that in a 5x2 setup, the software won’t take a majority of all the cluster members. I had assumed that all the cluster members would help form a quorum for the entire cluster.
Additionally, can you say that a replica 2 doesn’t help build an HA cluster. One must have a replica 3, or an arbiter volume. This let’s a person who specifically wants HA to avoid the mistake of replica 2.
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