Book Image

Ceph Cookbook - Second Edition

By : Karan Singh, Hackett, Umrao
Book Image

Ceph Cookbook - Second Edition

By: Karan Singh, Hackett, Umrao

Overview of this book

Ceph is a unified distributed storage system designed for reliability and scalability. This technology has been transforming the software-defined storage industry and is evolving rapidly as a leader with its wide range of support for popular cloud platforms such as OpenStack, and CloudStack, and also for virtualized platforms. Ceph is backed by Red Hat and has been developed by community of developers which has gained immense traction in recent years. This book will guide you right from the basics of Ceph , such as creating blocks, object storage, and filesystem access, to advanced concepts such as cloud integration solutions. The book will also cover practical and easy to implement recipes on CephFS, RGW, and RBD with respect to the major stable release of Ceph Jewel. Towards the end of the book, recipes based on troubleshooting and best practices will help you get to grips with managing Ceph storage in a production environment. By the end of this book, you will have practical, hands-on experience of using Ceph efficiently for your storage requirements.
Table of Contents (15 chapters)

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...