Re: [PVE-User] Corosync and Cluster reboot

[Iztok Gregori <iztok.gregori@elettra.eu>]

Hi!

On 07/01/25 15:15, DERUMIER, Alexandre wrote:
> Personnaly, I'll recommand to disable HA  temporary during the network change  (mv /etc/pve/ha/resources.cfg  to a tmp directory,  stop all pve-ha-lrm   , tehn stop all pve-ha-crm   to stop  the watchdog)
> 
> Then, after the migration, check the corosync logs during 1 or 2 days , and after that , if no retransmit occur, reenable HA.
> 

Good advice. But with the pve-ha-* services down the "HA-VMs" cannot 
migrate from a node to the other, because the migration is handled by 
the HA (or at least that is how I remember to happen some time ago). So 
I've (temporary) removed all the resources (VMs) from HA, which has the 
effect to tell "pve-ha-lrm" to disable the watchdog( "watchdog closed 
(disabled)" ) and no reboot should occur.

> It's really possible that it's a corosync bug (I remember to have had this kind of error with pve 7.X)

I'm leaning to a similar conclusion, but I'm still lacking in 
understanding of how corosync/watchdog is handled in Proxmox.

For example I still don't know who is updating the watchdog-mux service? 
Is corosync (but no "watchdog_device" is set in corosync.conf and by 
manual "if unset, empty or "off", no watchdog is used.") or is pve-ha-lrm?

I think that, after the migration, my best shot is to upgrade the 
cluster, but I have to understand if newer libcephfs client libraries 
support old Ceph clusters.

> Also, for "big" clusters (20-30 nodes), I'm using sctp protocol now, instead udp. for me , it's a lot more reliable when you have a network saturation on 1 now.
> 
> (I had the case of interne  udp flood attack coming from outside on 1 on my node, lagging the whole corosync cluster).²
> 
> 
> corosync.conf
> 
> totem {
>     cluster_name: ....
>     ....
>    interface {
>        knet_transport: sctp
>        linknumber: 0
>    }
>    ....
> 
> 
> (This need a full restart of corosync everywhere, and HA need to be disable before, because udp can't communite with sctp, so you'll have a loss of quorum during the change)

I've read about it, I think I'll follow your suggestion. In those bigger 
cluster have you tinker with corosync values as "token" or 
"token_retransmits_before_loss_const"?

Thank you!

Iztok


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