There comes a time in the life of a server when one is simply not enough. When that occurs, many organizations setup some type of server cluster. Each individual machine becomes a node that interfaces with the collective whole, rather than an individual server by itself.
There are several open source tools that you can use to managed a cluster.
Gluster – With unified file and object storage, scale-out storage for Apache Hadoop, and proactive self-healing, GlusterFS is a cluster file system that many of the innovative features that today’s large-scale application or web deployments need. Gluster can scale to several petabytes and can handle thousands of clients.
Linux-HA – Power high-end Linux systems since 1999, Linux-HA is designed for high availability cluster systems and includes several useful tools: a cluster messaging layer,resource agents, and a plumbing library and error reporting toolkit.
oneSIS – This tool is designed to make cluster management for Linux easier. It includes a flexible and simple mode for deployment and management, a master image that can be used for a diskless environment, allowing every machine to be controlled by a single system administration.
Pacemaker – A resource manager for small and large clusters, Pacemaker can monitor your cluster and automatically start recovery if something goes wrong. It also features support for quorate and resource-driven clusters, support for applications running on the same or different machines, multiple application modes, and more.
Managing a cluster is a big responsibility, but with some help from the above-mentioned tools, you may be able to make the experience a little easier.