[PVE-User] Corosync and Cluster reboot

[proxmox at elchaka.de]

Hello, 

Am 8. Januar 2025 11:12:02 MEZ schrieb Iztok Gregori <iztok.gregori at 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?

As far as i can say it's the pve-ha... service. 
If you dont use HA in your cluster, the watchdog isnt used.
Thats how i understand this. 

Hth

>
>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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