What `link_mode` values does corosync support?

Environment

• Red Hat Enterprise Linux Server 8, 9 (with the High Availability Add On)

Issue

• What link_mode values does corosync support?

Resolution

The link_mode attribute for corosync on RHEL 8+ determines how corosync determines which ring it uses to communicate with. A RHEL 8 cluster can have up to 8 knet rings used to communicate with other nodes in the cluster. If only one interface directive is specified, then link_mode: passive is automatically chosen. Currently only link_mode: passive is supported and the default for 1 or more corosync rings.

There are 3 possible values for link_mode: passive, active, or rr (round-robin).

• passive: The active link with the highest priority (highest number) will be used. If one or more links share the same priority the one with the lowest link ID will be used. This is the default link_mode if link_mode is not specified in the /etc/corosync/corosync.conf in the totem section. The value of passive is the only supported value for link_mode.
• active: All active links will be used simultaneously to send traffic. The knet_link_priority is ignored. The link mode active is not supported. For more information on why it is not supported then see: This content is not included.[RHEL-7647] Test Only bz to test liink_mode: active - Red Hat Issue Tracker.
• rr: Each packet will be sent to the next active link in round-robin order. The link mode rr is not supported. For more information on why it is not supported then see: This content is not included.[RHEL-7647] Test Only bz to test liink_mode: active - Red Hat Issue Tracker.

Related Articles

• Support Policies for RHEL High Availability Clusters - Cluster Interconnect Network Interfaces
• Support Policies for RHEL High Availability clusters - Transport Protocols

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