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

The ceph-objectstore tool


One of the key features of Ceph is its self-repairing and self-healing qualities. Ceph does this by keeping multiple copies of placement groups across different OSDs and ensures very high probability that you will not lose your data. In a very rare case, you may see the failure of multiple OSDs, where one or more PG replicas are on a failed OSD, and the PG state becomes incomplete, which leads to errors in the cluster health. For granular recovery, Ceph provides a low level PG and object data recovery tool known as ceph-objectstore-tool.

How to do it…

The ceph-objectstore-tool can be a risky operation, and the command needs to be run either as root or sudo. Do not attempt this on a production cluster without engaging the Red Hat Ceph Storage Support, unless you are sure of what you are doing. It can cause irreversible data loss in your cluster.

  1. Find incomplete PGs on your Ceph cluster. Using this command, you can get the PG id and its acting set:

    # ceph health detail...