Thank you all for your responses.
I guess the decision should be based on the 3rd host's connectivity to the rest of the cluster. If the 3rd host can only communicate over a single network then I might as well use the QDevice, otherwise a full blown node would be preferable to take full advantage of multiple networks.
The note about SBD fencing is also appreciated, will need to test it out.
Thanks again!
I guess the decision should be based on the 3rd host's connectivity to the rest of the cluster. If the 3rd host can only communicate over a single network then I might as well use the QDevice, otherwise a full blown node would be preferable to take full advantage of multiple networks.
The note about SBD fencing is also appreciated, will need to test it out.
Thanks again!
Gerry Sommerville
E-mail: [email protected]
----- Original message -----
From: "Klaus Wenninger" <[email protected]>
Sent by: "Users" <[email protected]>
To: "Strahil Nikolov" <[email protected]>, "Cluster Labs - All topics related to open-source clustering welcomed" <[email protected]>
Cc:
Subject: [EXTERNAL] Re: [ClusterLabs] QDevice vs 3rd host for majority node quorum
Date: Wed, Jul 14, 2021 4:20 AM
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On Tue, Jul 13, 2021 at 9:56 PM Strahil Nikolov <[email protected]> wrote:In some cases the third location has a single IP and it makes sense to use it as QDevice. If it has multiple network connections to that location - use a full blown node .If you are intending to use watchdog-fencing via sbd with a short watchdog-timeoutthat might speak for a full blown node as well. When using QDevice quorum-stateupdate may occur with a different delay (up to roughly 30s using the default) whichrequires watchdog-timeout to be long enough for the nodes to survive till that issettled and stonith-watchdog-timeout to be even longer to prevent split-brain.Best Regards,Strahil Nikolov_______________________________________________
On Tue, Jul 13, 2021 at 20:44, Andrei Borzenkov<[email protected]> wrote:On 13.07.2021 19:52, Gerry R Sommerville wrote:
> Hello everyone,
> I am currently comparing using QDevice vs adding a 3rd host to my
> even-number-node cluster and I am wondering about the details concerning network
> communication.
> For example, say my cluster is utilizing multiple heartbeat rings. Would the
> QDevice take into account and use the IPs specified in the different rings? Or
No.
> does it only use the one specified under the quorum directive for QDevice?
Yes. Remote device is unrelated to corosync rings. Qdevice receives
information of current cluster membership from all nodes (point of
view), computes partitions and selects partition that will remain quorate.
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