Book Image

Mastering Ceph

By : Nick Fisk
Book Image

Mastering Ceph

By: Nick Fisk

Overview of this book

Mastering Ceph covers all that you need to know to use Ceph effectively. Starting with design goals and planning steps that should be undertaken to ensure successful deployments, you will be guided through to setting up and deploying the Ceph cluster, with the help of orchestration tools. Key areas of Ceph including Bluestore, Erasure coding and cache tiering will be covered with help of examples. Development of applications which use Librados and Distributed computations with shared object classes are also covered. A section on tuning will take you through the process of optimisizing both Ceph and its supporting infrastructure. Finally, you will learn to troubleshoot issues and handle various scenarios where Ceph is likely not to recover on its own. By the end of the book, you will be able to successfully deploy and operate a resilient high performance Ceph cluster.
Table of Contents (12 chapters)

Extremely slow performance or no IO

If your cluster is performing really slowly, to the point that it is barely servicing IO requests, then there is probably an underlying fault or configuration issue. These slow requests will likely be highlighted on the Ceph status display with a counter for how long the request has been blocked. There are a number of things to check in this case.

Flapping OSDs

Check ceph.log on the monitors, and see whether it looks like any OSDs are flapping up and down. When an OSD joins a cluster, its PGs begin peering. During this peering process, IO is temporarily halted, so in the event of a number of OSD’s flapping, the client IO can be severely impacted. If there is evidence of flapping OSDs, the next step is to go through the logs...