Book Image

CentOS High Performance

By : Gabriel Cánepa
Book Image

CentOS High Performance

By: Gabriel Cánepa

Overview of this book

CentOS is the enterprise level Linux OS, which is 100% binary compatible to Red Hat Enterprise Linux (RHEL). It acts as a free alternative to RedHat's commercial Linux offering, with only a change in the branding. A high performance cluster consists in a group of computers that work together as one set parallel, hence minimizing or eliminating the downtime of critical services and enhancing the performance of the application. Starting with the basic principles of clustering, you will learn the necessary steps to install a cluster with two CentOS 7 servers. We will then set up and configure the basic required network infrastructure and clustering services. Further, you will learn how to take a proactive approach to the split-brain issue by configuring the failover and fencing of the cluster as a whole and the quorum of each node individually. Further, we will be setting up HAC and HPC clusters as a web server and a database server. You will also master the art of monitoring performance and availability, identifying bottlenecks, and exploring troubleshooting techniques. At the end of the book, you’ll review performance-tuning techniques for the recently installed cluster, test performance using a payload simulation, and learn the necessary skills to ensure that the systems, and the corresponding resources and services, are being utilized to their best capacity.
Table of Contents (13 chapters)
CentOS High Performance
About the Author
About the Reviewers


As explained previously, the output of pcs status under Failed actions will show you whether there are problems with the cluster resources and provide information as to what you should do in order to fix them.

Here is an example:

  • exit-reason='Config /var/lib/mariadb_drbd1/my.cnf doesn't exist': Make sure the configuration file for MariaDB exists and is identical on both nodes.

  • exit-reason='Couldn't find device [/dev/drbd1]. Expected /dev/??? to exist': The DRBD device was not created correctly. Review the instructions and try to create it.

As you can see, the exit reason will give you valuable information to troubleshoot and fix the issues you may have. If, after verifying the conditions outlined in the error messages, you are still experiencing issues with a particular resource, it is useful to clean up the operation history of a resource and redetect its current state:

pcs resource cleanup [resource name]

From Kamran, a real world problem scenario, which happens when the...