Heartbeat (software)

Heartbeat (software)
Name	Heartbeat
Developer	Red Hat, Linux-HA Project
Released	1996
Latest release version	3.x
Programming language	C (programming language), Shell script
Operating system	Linux kernel
Platform	x86, ARM architecture, PowerPC
License	GNU General Public License

Heartbeat (software) Heartbeat is a high-availability clustering component originating from the Linux-HA Project and later maintained by Red Hat that provides node membership, failover orchestration, and resource management for Unix-like systems. It integrates with other clustering middleware and resource agents to support services such as Apache HTTP Server, MySQL, PostgreSQL, and Dovecot in production environments. Heartbeat's role in resilient infrastructure places it among successors and contemporaries like Pacemaker (software), Corosync, and Keepalived.

Overview

Heartbeat implements cluster membership, fencing coordination, and resource monitoring for redundant systems designed to minimize downtime for services such as Nginx, Sendmail, Postfix, and OpenLDAP. It originated within the High-Availability Linux Project ecosystem and was adopted in enterprise distributions by Red Hat and contributors from projects like SUSE and Debian. Heartbeat coordinates with resource agents standardized by the Open Cluster Framework and integrates with tools used by operators at organizations such as NASA, CERN, and Netflix in their historical high-availability studies.

Architecture and Components

Heartbeat's architecture comprises daemons for cluster communication, membership, and arbitration that interact with resource agents and fencing devices. Core components include the heartbeat daemon, the cluster information base, and the resource agent interface compatible with the Linux Standard Base and the Open Cluster Framework (OCF). Networking relies on protocols compatible with IP (Internet Protocol), multicast, and unicast over interfaces managed by NetworkManager or manual configuration. Heartbeat cooperates with fencing mechanisms such as STONITH devices, IPMI, DRAC, and iLO to enforce split-brain prevention used by operators at Amazon Web Services and Microsoft Azure deployments. Integration points include the Linux Virtual Server stack, DRBD for block replication, and the Filesystem Hierarchy Standard for configuration.

Installation and Configuration

Installation pathways traditionally use package management systems like RPM Package Manager and dpkg via Yum (software), DNF (software), or APT (software). Configuration files reside under /etc and use syntax that references nodes, resources, and constraints; administrators apply configuration via init systems such as systemd or legacy SysV init. Typical deployment steps reference resource agent scripts from the Open Cluster Framework and utilize tools contributed by Red Hat engineers and community maintainers from Canonical. For storage-backed services administrators often combine Heartbeat with DRBD and configure fencing through IPMI, serial console servers, or power distribution unit controllers from vendors like APC (company).

High Availability Features and Functionality

Heartbeat provides failover policies, resource monitoring, node fencing coordination, and cluster membership arbitration to ensure continuity for services such as Bind (DNS), Samba (software), Kerberos-based authentication, and LDAP (Lightweight Directory Access Protocol). It implements resource start/stop/monitor operations via OCF-compliant scripts and supports constraints for ordering and colocation similar to primitives used in Pacemaker (software). Heartbeat's fencing support integrates with hardware management interfaces including IPMI and vendor management controllers used in datacenters run by Google and Facebook in published HA patterns. For load-balancing architectures Heartbeat teams with HAProxy or Linux Virtual Server to provide session continuity and graceful failover.

Use Cases and Deployments

Heartbeat has been used to build active-passive clusters for databases such as Oracle Database, MariaDB, and PostgreSQL, mail systems using Exim and Dovecot, and web stacks running Apache HTTP Server and Nginx. Large-scale scientific facilities like CERN and enterprises including Red Hat adopted patterns combining Heartbeat with DRBD and cluster-aware filesystems like GFS2 for service continuity. Telecommunications carriers and financial institutions often paired Heartbeat with specialized fencing hardware from vendors such as Schneider Electric and Dell EMC to meet stringent availability policies influenced by standards from bodies like ISO.

Development History and Licensing

Heartbeat traces to the mid-1990s within the High-Availability Linux Project and saw stewardship by contributors at Red Hat and community maintainers associated with SUSE and Debian. Over time, newer projects such as Pacemaker (software) and Corosync evolved from lessons learned in Heartbeat deployments, influencing the split of responsibilities between membership and resource management. Heartbeat was distributed under the GNU General Public License and accepted community contributions through mailing lists and version control systems used by projects hosted at organizations like SourceForge and later GitHub.

Security and Reliability Considerations

Operational security for Heartbeat clusters requires careful handling of authentication, encryption, and fencing to prevent unauthorized failover and split-brain scenarios; common mitigations include using IPsec, Transport Layer Security and management-plane isolation via Virtual Private Cloud constructs in public clouds such as Amazon Web Services and Microsoft Azure. Reliability practices incorporate periodic failover testing, use of OCF monitors, and integration with monitoring systems like Nagios, Zabbix, and Prometheus to surface health metrics. Vulnerability disclosures were historically coordinated through vendor channels at Red Hat and upstream maintainers, and administrators follow patching guidance aligned with standards from CVE reporting and advisories from vendors such as Canonical and SUSE.

Category:High-availability clustering