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

Full OSDs


By default, Ceph will warn when OSD utilization approaches 85%, and it will stop write I/O to the OSD when it reaches 95%. If, for some reason, the OSD completely fills up to 100%, then the OSD is likely to crash and will refuse to come back online. An OSD that is above the 85% warning level will also refuse to participate in backfilling, so the recovery of the cluster may be impacted when OSDs are in a near full state.

Before covering the troubleshooting steps around full OSDs, it is highly recommended that you monitor the capacity utilization of your OSDs, as described in the monitoring chapter. This will give you advanced warning as OSDs approach the near_full warning threshold.

If you find yourself in a situation where your cluster is above the near full warning state, you have two main options:

  1. Add some more OSDs.
  2. Delete some data.

However, in the real world, both of these are either impossible or will take time, in which case the situation can deteriorate. If the OSD is only at...