[PVE-User] Corosync and Cluster reboot

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

Hi to all!

I need some help to understand a situation (cluster reboot) which 
happened to us previous week. We are running a 17 nodes Proxmox cluster 
with a separate Ceph cluster for storage (no hyper-convergence).

We have to upgrade a stack a 2 switches and in order to avoid any 
downtime we decided to prepare a new (temporary) stack and move the 
links from one switch to the other. Our procedure was the following:

- Migrate all the VM from node.
- Unplug the links from the old switch.
- Plug the links to the temporary switch.
- Wait till the node is available again in the cluster.
- Repeat.

We have to move 8 nodes from one switch to the other. The first 4 nodes 
went smoothly, but when we did plug the 5th node into the new switch ALL 
the nodes which have configured HA VMs rebooted!

 From the Corosync logs I see that the Token wasn't received and because 
of that watchdog-mux wasn't updated causing the node reboot.

Here are the Corosync logs during the procedure and before the nodes 
restarted. It was captured from a node which didn't reboot (pve-ha-lrm: 
idle):

> 12:51:57 [KNET  ] link: host: 18 link: 0 is down
> 12:51:57 [KNET  ] host: host: 18 (passive) best link: 0 (pri: 1)
> 12:51:57 [KNET  ] host: host: 18 has no active links
> 12:52:02 [TOTEM ] Token has not been received in 9562 ms
> 12:52:16 [QUORUM] Sync members[16]: 1 2 3 4 7 8 9 10 11 12 13 14 15 16 17 19
> 12:52:16 [QUORUM] Sync left[1]: 18
> 12:52:16 [TOTEM ] A new membership (1.d29) was formed. Members left: 18
> 12:52:16 [TOTEM ] Failed to receive the leave message. failed: 18
> 12:52:16 [QUORUM] Members[16]: 1 2 3 4 7 8 9 10 11 12 13 14 15 16 17 19
> 12:52:16 [MAIN  ] Completed service synchronization, ready to provide service.
> 12:52:42 [KNET  ] rx: host: 18 link: 0 is up
> 12:52:42 [KNET  ] host: host: 18 (passive) best link: 0 (pri: 1)
> 12:52:50 [TOTEM ] Token has not been received in 9567 ms
> 12:53:01 [TOTEM ] Token has not been received in 20324 ms
> 12:53:11 [QUORUM] Sync members[16]: 1 2 3 4 7 8 9 10 11 12 13 14 15 16 17 19
> 12:53:11 [TOTEM ] A new membership (1.d35) was formed. Members
> 12:53:20 [TOTEM ] Token has not been received in 9570 ms
> 12:53:31 [TOTEM ] Token has not been received in 20326 ms
> 12:53:41 [QUORUM] Sync members[16]: 1 2 3 4 7 8 9 10 11 12 13 14 15 16 17 19
> 12:53:41 [TOTEM ] A new membership (1.d41) was formed. Members
> 12:53:50 [TOTEM ] Token has not been received in 9570 ms 

And here you can find the logs of a successfully completed "procedure":

> 12:19:12 [KNET  ] link: host: 19 link: 0 is down
> 12:19:12 [KNET  ] host: host: 19 (passive) best link: 0 (pri: 1)
> 12:19:12 [KNET  ] host: host: 19 has no active links
> 12:19:17 [TOTEM ] Token has not been received in 9562 ms
> 12:19:31 [QUORUM] Sync members[16]: 1 2 3 4 7 8 9 10 11 12 13 14 15 16 17 18
> 12:19:31 [QUORUM] Sync left[1]: 19
> 12:19:31 [TOTEM ] A new membership (1.d21) was formed. Members left: 19
> 12:19:31 [TOTEM ] Failed to receive the leave message. failed: 19
> 12:19:31 [QUORUM] Members[16]: 1 2 3 4 7 8 9 10 11 12 13 14 15 16 17 18
> 12:19:31 [MAIN  ] Completed service synchronization, ready to provide service.
> 12:19:47 [KNET  ] rx: host: 19 link: 0 is up
> 12:19:47 [KNET  ] host: host: 19 (passive) best link: 0 (pri: 1)
> 12:19:50 [QUORUM] Sync members[17]: 1 2 3 4 7 8 9 10 11 12 13 14 15 16 17 18 19
> 12:19:50 [QUORUM] Sync joined[1]: 19
> 12:19:50 [TOTEM ] A new membership (1.d25) was formed. Members joined: 19
> 12:19:51 [QUORUM] Members[17]: 1 2 3 4 7 8 9 10 11 12 13 14 15 16 17 18 19
> 12:19:51 [MAIN  ] Completed service synchronization, ready to provide service. 

Comparing the 2 logs I can see that after the "host: 18" link was found 
active again the token was not received, but I cannot figure out what 
went different in this case.

I have 2 possible culprits:

1. NETWORK

The cluster network is backed up with 5 Extreme Networks switches, 3 
stacks of two x870 (100GBE), 1 stack of two x770 (40GBE) and one 
temporary stack of two 7720-32C (100GBE). The switches are linked 
together by a 2x LACP bond, and the 99% of the cluster communication are 
on 100GBE.

The hosts are connected to the network with different speed interfaces: 
10GBE (1 node), 25GBE (4 nodes), 40GBE (1 node), 100GBE (11 nodes). All 
the nodes are bonded, the Corosync network (is the same as the 
management one) is defined on a bridge interface on the bonded link 
(configuration is almost the same on all nodes, some older ones have 
balance-xor the other have lacp as bonding mode).

Is it possible that there is something wrong with the network, but I 
cannot find a probable cause. From the data that I have, I don't see 
nothing special, no links were saturated, no error logged...

2. COROSYNC

The cluster is running a OLD version of Proxmox (7.1-12) with Corosync 
3.1.5-pve2. Is possible that there is a problem in Corosync fixed in a 
later release. I did a quick search but I didn't found anything. The 
cluster upgrade is on my to-do list (but the list is huge, so it will 
not be done tomorrow).

We are running only one Corosync network which is the same as the 
management/migration one, but different from the one for 
client/storage/backup. The configuration is very basic, I think is the 
default one, I can provide it if needed.

I checked the Corosync stats and the average latency is around 150 
(microseconds?) along all links on all nodes.

====

In general it can be a combination of the 2 above or something 
completely different.

Do you have some advice on where to look to debug further?

I can provide more information if needed.

Thanks a lot!

Iztok



-- 
Iztok Gregori
ICT Systems and Services
Elettra - Sincrotrone Trieste S.C.p.A.
Telephone: +39 040 3758948
http://www.elettra.eu

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