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

Investigating asserts


Assertions are used in Ceph to ensure that during the execution of the code any assumptions that have been made about the operating environment remain true. These assertions are scattered throughout the Ceph code and are designed to catch any conditions that may go on to cause further problems if the code is not stopped.

If you trigger an assertion in Ceph, it's likely that some form of data has a value that is unexpected. This may be caused by some form or corruption or unhandled bug.

If an OSD causes an assert and refuses to start anymore, the usual recommended approach would be to destroy the OSD, recreate it, and then let Ceph backfill objects back to it. If you have a reproducible failure scenario, then it is probably also worth filing a bug in the Ceph bug tracker.

As mentioned several times in this chapter, OSDs can fail either due to hardware faults or soft faults in either the stored data or OSD code. Soft faults are much more likely to affect multiple OSDs at...