[SOLVED] Voting-only quorum node?

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Odin5000

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Jun 21, 2016
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Hello all,

I'm looking at really tight rack, power, and network requirements for an upcoming PVE4.2 deploy. I got the idea that I could deploy a 3 node cluster (with shared storage) with 1 of the nodes only acting to vote in the quorum for HA. The idea being that I don't currently have enough room for a 3rd real node until a date months from now, but have to deploy the system now.

My idea is to use an Intel NUC as the 3rd node, but obviously I don't want any VMs to actually run from there. I'm just looking to satisfy PVE's 3-node requirement, which is a good requirement to have, I understand why it's there, I just need to work around it for now and accept the risk that comes with it.

So is this a design that will work? How can I set that node to not allow VM's to run from it, but still participate in the cluster? I realize the NUC has single power supply, single network jack, etc. However, the alternative is not enabling HA on the VM's, which I would very much like to do. If there is a better way to go about running this system now, I'm all ears.

Thoughts? Criticisms?
 
Simply create a HA-group which only have the node members you want to have VM's running on. I am testing a setup currently where I use a Rasberry Pi as a quorum only node. Seems to work excellent so in due time I will make the howto public available.
 
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Thanks for your reply, Mir. I just looked up the HA Groups and it seems perfect. Reading up on it, I have a questions regarding this comment on the wiki:

"If you enable HA it's not possible to turnoff the VM inside the VM. Also, if it is disabled the VM will be stopped."

Does this mean that if I need to shut down a VM, I should stop the important services and then use the 'shutdown' command from the PVE UI?

Additionally, if I create VM's by just going to 'Create VM' in the upper-right hand corner of the UI, will they automatically be marked for HA? Or if I want to create a new VM should I do it from the HA > Add... page?

Again, thanks for your quick reply!
 
If you need to shutdown a VM simply disable HA for this VM. (See HA->Resources (Double-click the VM and set state to disabled))
No VM will automatically be HA enabled - you must add it for HA in the Datacenter HA tab.
 
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Fantastic. Last question (swear) - even though I only have 2 nodes participating in the HA group, the quorum will still use 3 nodes in it's vote? So that means that the HA group and the nodes voting in the quorum are mutually exclusive factors?

My concern is running a 2-node HA group might fall into a scenario where 1 host fails, and the other host shuts itself down due to only having 1 vote available in the HA Group, but if the cluster quorum and HA Group are separate calculations entirely, I think this plan just might work!
 
quorum is formed over all nodes and has nothing to do with HA-groups. As long as 2 of the 3 nodes is alive, regardless of HA-group member or not, you have quorum and VMs will be running on either of the HA-group members which is available at any given time.
 
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