[PVE-User] cluster numbers

[Jeff Palmer]

By default, in a 4 node cluster, 3 members would need to agree for quorum,
not 2.  In your example, if 2 hosts split from the other 2 hosts, neither
side will have quorum.  No split brain in that scenario.

Think of quorum as a 'majority wins' vote. If the vote is a tie, there is
no winner.

On Apr 11, 2017 10:56 AM, "Alessandro Briosi" <ab1 at metalit.com> wrote:

> Hi all,
> I have a question about cluster quorum (proxmox 4).
>
> I currently have a 3 host cluster with shared storage (gluster).
>
> I have an old machine which I could use as a backup/service in case of
> some host failure, though adding this server to the cluster would make
> the cluter composed of 4 hosts which could possibly lead to a split
> brain in case of 2 hosts separated from the other 2 hosts (remote but
> possible).
>
> Should the cluster always be composed by an odd number of hosts?
>
> I'm not using HA so if I move some VM from one host to the other I'm
> aware of what the current situation is.
>
> In case of a split brain am I able to say which cluster part has quorum?
>
> Thank you,
> Alessandro
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