repmgr is the most popular tool for PostgreSQL failover, introduced by 2ndQuadrant in 2010.
repmgr helps DBAs and System Administrators manage a cluster of PostgreSQL databases. By taking advantage of the Hot Standby capability introduced in PostgreSQL 9, repmgr greatly simplifies the process of setting up and managing databases with high availability and scalability requirements.
repmgr simplifies administration and daily management, enhances productivity and reduces the overall costs of a PostgreSQL cluster by:
- Monitoring the replication process
- Allowing DBAs to issue high availability operations such as switch-overs and fail-overs.
(repmgr v3.3 released - January 6, 2017)
repmgr is available via 2ndQuadrant’s YUM repository for the Red Hat family (RHEL, CentOS, and Fedora) and PGDG's APT repository for Debian. You can use standard yum and apt package managers for installing repmgr with your instance of PostgreSQL.
- repmgr 3.x requires PostgreSQL 9.3 or higher
- repmgr 2.x requires PostgreSQL 9.1 or 9.2
The images and explanation below represent some of the most common configurations of repmgr in production databases.
1 Primary + 1 Standby
Here, repmgr is configured on Standby for failover in case the Primary node fails.
1 Primary + 2 Standbys
Here, repmgr is configured on 2 Standby nodes for failover in case the Primary node fails. Additional Standby node is configured for High Availability (HA) so at least one Standby is still present after failover.
1 Primary + 3 Standbys + 1 Witness
Here, the Standby in Location B is a last resort in case Location A becomes entirely unavailable. The Witness server here ensures that in case of network interruption between the two locations, the Standby at Location B does not promote itself to Primary, i.e. prevents the Split Brain scenario.
repmgr is free and open-source software licensed under the . This means you are free to use and modify repmgr as you see fit, however any modifications you make may only be distributed under the same terms. .
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