Book Image

Mastering Ceph, - Second Edition

By : Nick Fisk
Book Image

Mastering Ceph, - Second Edition

By: Nick Fisk

Overview of this book

Ceph is an open source distributed storage system that is scalable to Exabyte deployments. This second edition of Mastering Ceph takes you a step closer to becoming an expert on Ceph. You’ll get started by understanding the design goals and planning steps that should be undertaken to ensure successful deployments. In the next sections, you’ll be guided through setting up and deploying the Ceph cluster with the help of orchestration tools. This will allow you to witness Ceph’s scalability, erasure coding (data protective) mechanism, and automated data backup features on multiple servers. You’ll then discover more about the key areas of Ceph including BlueStore, erasure coding and cache tiering with the help of examples. Next, you’ll also learn some of the ways to export Ceph into non-native environments and understand some of the pitfalls that you may encounter. The book features a section on tuning that will take you through the process of optimizing both Ceph and its supporting infrastructure. You’ll also learn to develop applications, which use Librados and distributed computations with shared object classes. Toward the concluding chapters, you’ll learn to troubleshoot issues and handle various scenarios where Ceph is not likely to recover on its own. By the end of this book, you’ll be able to master storage management with Ceph and generate solutions for managing your infrastructure.
Table of Contents (18 chapters)
Free Chapter
Section 1: Planning And Deployment
Section 2: Operating and Tuning
Section 3: Troubleshooting and Recovery

Using the Ceph object-store tool

Hopefully, if you have followed best practices, your cluster is running with three replicas and is not configured with any dangerous configuration options. Ceph, in most cases, should be able to recover from any failure.

However, in the scenario where a number of OSDs go offline, a number of PGs and/or objects may become unavailable. If you are unable to reintroduce these OSDs back into the cluster to allow Ceph to recover them gracefully, the data in those PGs is effectively lost. However, there is a possibility that the OSD is still readable to use the objectstore tool to recover the PGs contents. The process involves exporting the PGs from the failed OSDs and then importing the PGs back into the cluster. The objectstore tool requires that the OSDs' internal metadata is still in a consistent state, so full recovery is not guaranteed.