In the dark past, configuring Pacemaker required the administrator to read and write XML. In true UNIX style, there were also a number of different commands that specialized in different aspects of querying and updating the cluster.

All of that has been greatly simplified with the creation of unified command-line shells (and GUIs) that hide all the messy XML scaffolding.

These shells take all the individual aspects required for managing and configuring a cluster, and packs them into one simple to use command line tool.

They even allow you to queue up several changes at once and commit them atomically.

There are currently two command-line shells that people use, pcs and crmsh. This edition of Clusters from Scratch is based on lcmc. Start by taking some time to familiarize yourself with what it can do.

# lcmc