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

Working with RBD snapshots


Ceph extends full support to snapshots, which are point-in-time, read-only copies of an RBD image. You can preserve the state of a Ceph RBD image by creating snapshots and restoring the snapshot to get the original data.

If you take a snapshot of an RBD image while I/O is in progress to the image the snapshot may be inconsistent. If this occurs you will be required to clone the snapshot to a new image for it to be mountable. When taking snapshots it is recommended to cease I/O from the application to the image before taking the snapshot. This can be done by customizing the application to issue a freeze before a snapshot or can manually be done using the fsfreeze command (man page for fsfreeze details this command further).   

How to do it...

Let's see how a snapshot works with Ceph:

  1. To test the snapshot functionality of Ceph, let's create a file on the block device that we created earlier:

         # echo "Hello Ceph This is snapshot test" 
           > /mnt/ceph...