Architecting FreePBX High Availability Clusters Using Pacemaker
by Provider Adminlast verified 2026-08-13
Overview
Learn how to design, configure, and maintain an enterprise-grade FreePBX High Availability (HA) cluster using Pacemaker, Corosync, and DRBD. This guide covers active-passive failover architecture, shared storage replication, cluster constraints, STONITH fencing, and SIP endpoint persistence strategies to ensure maximum uptime for critical voice services.
Key takeaways
- Understand the active-passive HA architecture utilizing Corosync messaging and Pacemaker resource orchestration.
- Implement DRBD block-level replication to keep Asterisk configuration, CDRs, and voicemail synchronized.
- Configure Pacemaker resource sets, order constraints, and colocation rules for seamless service failover.
- Eliminate split-brain conditions using hardware STONITH fencing and proper quorum configuration.
- Optimize PJSIP registration intervals and gratuitous ARP behavior to minimize audio downtime during failover.
Prerequisites
- Two dedicated physical servers or VMs with identical network interfaces and storage configurations.
- Root access with static IP addresses configured on both cluster nodes.
- A dedicated private network interface (NIC) for cluster heartbeat and DRBD storage synchronization.
- Basic knowledge of Asterisk, Linux systemd services, and Pacemaker/Corosync cluster administration.
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