Capítulo 6. Clustering

The keepalived package is now fully supported. The keepalived package provides simple and robust facilities for load-balancing and high-availability. The load-balancing framework relies on the well-know and widely used Linux Virtual Server kernel module providing Layer4 network load-balancing. The keepalived daemon implements a set of health checkers to load-balanced server pools according to their state. The keepalived daemon also implements the Virtual Router Redundancy Protocol (VRRP), allowing router or director failover to achieve high availability.

The haproxy package is now fully supported. HAProxy is a stand-alone, layer-7, high-performance network load balancer for TCP and HTTP-based applications which can perform various types of scheduling based on the content of the HTTP requests.

Red Hat Enterprise Linux 6.6 contains a new version of the CTDB agent, in which some internal operations have changed to improve stability and reliability. As a consequence, the new version cannot be mixed with older versions running in parallel in the same cluster. To update CTDB in an existing cluster, CTDB must be stopped on all nodes in the cluster before the upgrade starts, and the nodes can then be updated one by one and started again.