[PVE-User] Undo pvecm

[Thomas Lamprecht]

Hi,

On 07/05/2016 09:53 PM, William Gnann wrote:
> Hi,
>
> I have created a cluster with two nodes to concentrate the administration of my machines within a single interface. But one of the machines got some hardware problem and went down.
>
> I ran "pvecm e 1" to bring back the master node to quorate state and excluded the node with hardware problem.
>
> Should I undo the cluster configuration since it will take a time to restore the other node?

Hmm, I'd do so as else you have to set the expected votes always to 1 if 
you reboot the current working node.
If you expected to reinstall the other node then you have to delete the 
node one way or the other some time.
If you expect to repair it then you could also let the config like it is 
so that it may join the cluster again if repaired.

It causes trouble if you delete it from the cluster config via `pvecm 
delnode NODENAME` but bring it back online in the same config, in this 
case you have to delete the following files from the repaired node:

# set also here expected votes to 1 if you have no quorum.
rm /etc/pve/corsync.conf
rm /var/lib/corosync/ringid*
rm /etc/corosync/*

Do that before you bring the node online in the cluster again (else it 
wants to join the cluster where the other node has deletet it).

> Finally, was it a bad idea to use the cluster configuration (without HA) to concentrate the machine administration?

No, i think that is really convenient and clustering (with or without 
HA) is a central aspect of Proxmox VE so I see no problems here.
But clustering nodes means also that you establish a dependency between 
the nodes, the now need quorum (the majority of votes from the nodes in 
the cluster) do execute cluster actions to ensure everything is working 
correctly.

So this implies that clustering a stable node with a node expected to 
often go down, or being unreliable in other ways has its drawbacks on 
two node clusters.
Also as a rule of thumb, the more the better :) HA is achievable with 3+ 
Nodes.

cheers,
Thomas