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<p class="MsoNormal"><span style="font-size:11.0pt">Hi Team,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Issue : We are performing a rolling upgrade from Pacemaker v2.1.6 to v3.0.1 in a two-node cluster.
</span><span lang="EN-US">According to the [Pacemaker 3.0 Changes documentation](
</span><a href="https://projects.clusterlabs.org/w/projects/pacemaker/pacemaker_3.0_changes/"><span style="font-family:"Segoe UI Emoji",sans-serif">⚡</span> Pacemaker 3.0 Changes</a><span lang="EN-US"> ), rolling upgrades from Pacemaker 2.0.0 and later should
be supported with minimal changes.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">However, after upgrading the first node (Node 1) to Pacemaker 3.0.1, the second node (Node 2) running Pacemaker 2.1.6 is unable to connect to the cluster after reboot of node2. Pacemaker fails to start on
Node 2 with the error:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Error: error running crm_mon, is pacemaker running?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> crm_mon: Connection to cluster failed: Connection refused<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Expected Behaviour:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">During a rolling upgrade, both nodes should remain operational and communicate with each other until the second node is upgraded. The non-upgraded node (2.1.6) should continue to function while the upgraded
node (3.0.1) acts as DC.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Questions:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">1. Is this a known limitation with the rolling upgrade path from 2.1.6 to 3.0.1?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">2. Are there specific compatibility issues between Pacemaker 3.0.1 and 2.1.6 that prevent cluster communication?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">3. Are there any additional logs or diagnostic information needed to troubleshoot this issue?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Environment:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">- Cluster: 2-node RHEL 8 cluster with Corosync<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">- Node 1 (node1): Upgraded to Pacemaker 3.0.1-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">- Node 2 (node2): Running Pacemaker 2.1.6-1.el8 (not yet upgraded)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Node 1 (node1) - Upgraded:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Pacemaker: 3.0.1-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Corosync: 3.1.10-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">PCS: 0.12.2-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1: 1.33-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">resource-agents: 4.17.0-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Node 2 (node2) - Not Upgraded:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Pacemaker: 2.1.6-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Corosync: 3.1.7-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">PCS: 0.10.19-2.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1: 1.25-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">resource-agents: 4.12.0-1.el8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Node1:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">[root@node1 testadmin]# pcs status pcsd<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> node1: Online<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> node2: Online<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">[root@node1 testadmin]# pcs status<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Cluster Summary:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> * Stack: corosync (Pacemaker is running)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> * Current DC: node1 (version 3.0.1-1.el8-3.0.1) - partition with quorum<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> * Last updated: Sat Feb 7 11:39:00 2026 on node1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> * Last change: Sat Feb 7 11:22:01 2026 by hacluster via hacluster on node1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> * 2 nodes configured<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> * 23 resource instances configured (2 DISABLED)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="DA" style="font-size:11.0pt">Node List:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="DA" style="font-size:11.0pt"> * Online: [ node1 ]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="DA" style="font-size:11.0pt"> * OFFLINE: [ node2 ]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="DA" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Full List of Resources:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> * SNMP_node2 (ocf:pacemaker:ClusterMon): Stopped<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> * SNMP_node1 (ocf:pacemaker:ClusterMon): Started node1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Daemon Status:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> corosync: active/enabled<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> pacemaker: active/enabled<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> pcsd: active/enabled<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">[root@node1 testadmin]# rpm -qa | egrep "pcs|pacemaker|corosy|pacemak|resource-a|libknet"<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-lz4-plugin-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-zstd-plugin-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-crypto-plugins-all-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-libs-3.0.1-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pcs-0.12.2-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">corosynclib-3.1.10-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-bzip2-plugin-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-lzma-plugin-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-zlib-plugin-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-plugins-all-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-crypto-openssl-plugin-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-plugins-all-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-schemas-3.0.1-1.el8.noarch<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-cluster-libs-3.0.1-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-3.0.1-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">corosync-3.1.10-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-lzo2-plugin-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-crypto-nss-plugin-1.33-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">resource-agents-4.17.0-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-cli-3.0.1-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">[root@node1 testadmin]#<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Node2:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">[root@node2 testadmin]# pcs status<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Error: error running crm_mon, is pacemaker running?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> crm_mon: Connection to cluster failed: Connection refused<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">[root@node2 testadmin]# pcs status pcsd<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> node2: Online<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> node1: Online<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">[root@node2 testadmin]#<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">[root@node2 testadmin]# rpm -qa | egrep "pcs|pacemaker|corosy|pacemak|resource-a|libknet"<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-bzip2-plugin-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-zlib-plugin-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-crypto-openssl-plugin-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-schemas-2.1.6-1.el8.noarch<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-2.1.6-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">corosync-3.1.7-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-lz4-plugin-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-lzo2-plugin-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-zstd-plugin-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-crypto-nss-plugin-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-crypto-plugins-all-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">resource-agents-4.12.0-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-libs-2.1.6-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-cli-2.1.6-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pcs-0.10.19-2.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">corosynclib-3.1.7-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-lzma-plugin-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-compress-plugins-all-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">libknet1-plugins-all-1.25-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">pacemaker-cluster-libs-2.1.6-1.el8.x86_64<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Thanks and Regards,<br>
S Sathish S<o:p></o:p></span></p>
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