Book Image

Ceph Cookbook

Book Image

Ceph Cookbook

Overview of this book

Ceph is a unified, distributed storage system designed for excellent performance, reliability, and scalability. This cutting-edge technology has been transforming the storage industry, and is evolving rapidly as a leader in software-defined storage space, extending full support to cloud platforms such as Openstack and Cloudstack, including virtualization platforms. It is the most popular storage backend for Openstack, public, and private clouds, so is the first choice for a storage solution. Ceph is backed by RedHat and is developed by a thriving open source community of individual developers as well as several companies across the globe. This book takes you from a basic knowledge of Ceph to an expert understanding of the most advanced features, walking you through building up a production-grade Ceph storage cluster and helping you develop all the skills you need to plan, deploy, and effectively manage your Ceph cluster. Beginning with the basics, you’ll create a Ceph cluster, followed by block, object, and file storage provisioning. Next, you’ll get a step-by-step tutorial on integrating it with OpenStack and building a Dropbox-like object storage solution. We’ll also take a look at federated architecture and CephFS, and you’ll dive into Calamari and VSM for monitoring the Ceph environment. You’ll develop expert knowledge on troubleshooting and benchmarking your Ceph storage cluster. Finally, you’ll get to grips with the best practices to operate Ceph in a production environment.
Table of Contents (18 chapters)
Ceph Cookbook
Credits
Foreword
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Placement group states


Ceph PGs may exhibit several states based on what's happening inside the cluster at that point in time. To know the state of a PG, you can see the output of the command ceph status. In this recipe, we will cover these different states of PGs and understand what each state actually means:

  • Creating: The PG is being created. This generally happens when pools are being created or when PGs are increased for a pool.

  • Active: All PGs are active, and requests to the PG will be processed.

  • Clean: All objects in the PG are replicated the correct number of times.

  • Down: A replica with necessary data is down, so the PG is offline (down).

  • Replay: The PG is waiting for clients to replay operations after an OSD has crashed.

  • Splitting: The PG is being split into multiple PGs. Usually, a PG attains this state when PGs are increased for an existing pool. For example, if you increase the PGs of a pool rbd from 64 to 128, the existing PGs will split, and some of their objects will be moved...