What's a Totem "Retransmit List" all about in Corosync?

Occasionally, you may see errors similar to this in your system logs:

corosync [TOTEM ] Retransmit List: e4 e5 e7 e8 ea eb ed ee

Here's what causes them, and what you can do to fix the issue.

Corosync, more specifically its Totem protocol implementation, defines a maximum number of cluster …

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Solve a DRBD split-brain in 4 steps

Whenever a DRBD setup runs into a situation where the replication network is disconnected and fencing policy is set to dont-care (default), there is the potential risk of a split-brain. Even with resource level fencing or STONITH setup, there are corner cases that will end up in a split-brain.

When …

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Checking Corosync cluster membership

It's simple and easy to get Pacemaker's view of the status of members in a cluster – just invoke crm_mon. But what if you want to check on the cluster membership when Pacemaker is not running, or you want to make sure whether Corosync's view of the cluster is identical to …

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Fencing in Libvirt/KVM virtualized cluster nodes

Often, people deploy the Pacemaker stack in virtual environments for purposes of testing and evaluation. In such environments, it's easy to test Pacemaker's fencing capabilities by tying in with the hypervisor.

This quick howto illustrates how to configure fencing for two virtual cluster nodes hosted on a libvirt/KVM hypervisor …

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