Corosync Last Man standing

[ermanishchawla]

Does proxmox support, corosync last man standing ?
I have a 8 node cluster and 8 nodes are divided into two chassis ( each chassis having 4 Nodes). Now if there is power outage due to any thing in one of the chassis
I will only have a 4 node cluster and thus no quorum.

I read in corosync documentation about last man standing algorithm
Using the above 8 node cluster example, with LMS enabled the cluster can retain quorum and continue operating by losing, in a cascade fashion, up to 6 nodes with only 2 remaining active.

Example chain of events:

1) cluster is fully operational with 8 nodes.
(expected_votes: 8 quorum: 5)
2) 3 nodes die, cluster is quorate with 5 nodes.
3) after last_man_standing_window timer expires,
expected_votes and quorum are recalculated.
(expected_votes: 5 quorum: 3)
4) at this point, 2 more nodes can die and
cluster will still be quorate with 3.
5) once again, after last_man_standing_window
timer expires expected_votes and quorum are
recalculated.
(expected_votes: 3 quorum: 2)
6) at this point, 1 more node can die and
cluster will still be quorate with 2.
7) one more last_man_standing_window timer
(expected_votes: 2 quorum: 2)

My question is how to enable the same in the proxmox, any configuration changed to be done

 

[ermanishchawla]

This is what i changed
quorum {
provider: corosync_votequorum
last_man_standing: 1
last_man_standing_window: 20000
}
and it worked only after long wait


and pvecm status shows the following


Votequorum information
----------------------
Expected votes: 4
Highest expected: 4
Total votes: 4
Quorum: 3
Flags: Quorate LastManStanding

So now my question is it should have been enabled by 20 seconds as per the config, why it took 20 minutes? whether my understanding is wrong

 

[t.lamprecht]

Does proxmox support, corosync last man standing ?

No, we do not support it. If this makes issues, and it will sooner or later, you're completely on your own.

I heavily advise to not use it. Go back to normal votequorum, use a QDevice if you want a two or four nodes + one setup.

 

[RolandK]

i know this is not supported and we are on our own - but from my first experiments ( 1st node is a VM and is always up) , last man standing clustering scenario seems to work

https://forum.proxmox.com/threads/proxmox-farm-instead-of-cluster.128753/#post-563335