[ClusterLabs] last_man_standing (LMS) and wait_for_all (WFA)

[Faaland, Olaf P.]

I should say we deal with the common startup race described in votequorum(5), whereby nodes that don’t come up are fenced once quorum is attained, by other means.

-Olaf

From: Faaland, Olaf P. <faaland1 at llnl.gov>
Date: Friday, May 2, 2025 at 10:25 AM
To: users at clusterlabs.org <users at clusterlabs.org>
Subject: last_man_standing (LMS) and wait_for_all (WFA)
Hi,

In votequorum(5), discussing last_man_standing (LMS) and wait_for_all (WFA) with corosync-3.1.8-1.el8.x86_64, it says:


Enabling LMS allows the cluster to dynamically recalculate expected_votes and quorum under specific circumstances. It is essential to enable WFA when using LMS in High Availability clusters.

Why is that essential?

I have many, many clusters, and there will be times when a node is down because we need replacement parts or something similar, and the cluster must be rebooted (e.g. an OS update).

Thanks!
Olaf
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