Book Image

Ceph: Designing and Implementing Scalable Storage Systems

By : Michael Hackett, Vikhyat Umrao, Karan Singh, Nick Fisk, Anthony D'Atri, Vaibhav Bhembre
Book Image

Ceph: Designing and Implementing Scalable Storage Systems

By: Michael Hackett, Vikhyat Umrao, Karan Singh, Nick Fisk, Anthony D'Atri, Vaibhav Bhembre

Overview of this book

This Learning Path takes you through the basics of Ceph all the way to gaining in-depth understanding of its advanced features. You’ll gather skills to plan, deploy, and manage your Ceph cluster. After an introduction to the Ceph architecture and its core projects, you’ll be able to set up a Ceph cluster and learn how to monitor its health, improve its performance, and troubleshoot any issues. By following the step-by-step approach of this Learning Path, you’ll learn how Ceph integrates with OpenStack, Glance, Manila, Swift, and Cinder. With knowledge of federated architecture and CephFS, you’ll use Calamari and VSM to monitor the Ceph environment. In the upcoming chapters, you’ll study the key areas of Ceph, including BlueStore, erasure coding, and cache tiering. More specifically, you’ll discover what they can do for your storage system. In the concluding chapters, you will develop applications that use Librados and distributed computations with shared object classes, and see how Ceph and its supporting infrastructure can be optimized. By the end of this Learning Path, you'll have the practical knowledge of operating Ceph in a production environment. This Learning Path includes content from the following Packt products: • Ceph Cookbook by Michael Hackett, Vikhyat Umrao and Karan Singh • Mastering Ceph by Nick Fisk • Learning Ceph, Second Edition by Anthony D'Atri, Vaibhav Bhembre and Karan Singh
Table of Contents (27 chapters)
Title Page
About Packt
Contributors
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 a very high probability that you will not lose your data. In very rare cases, 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.

Note

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.

How to do it...

Let's run through some example uses for the ceph-objectstore-tool:

  1. Find incomplete PGs on your Ceph cluster. Using this...