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
1
Section 1: Planning And Deployment
6
Section 2: Operating and Tuning
13
Section 3: Troubleshooting and Recovery

Large monitor databases

Ceph monitors use leveldb to store all of the required monitor data for your cluster. This includes things such as the monitor map, OSD map, and PG map, which OSDs and clients pull from the monitors to be able to locate objects in the RADOS cluster. One particular feature that you should be aware of is that during a period where the health of the cluster doesn't equal HEALTH_OK, the monitors do not discard any of the older cluster maps from its database. If the cluster is in a degraded state for an extended period of time and/or the cluster has a large number of OSDs, the monitor database can grow very large.

In normal operating conditions, the monitors are very lightweight on resource consumption; because of this, it's quite common for smaller disk sizes to be used for the monitors. In the scenario where a degraded condition continues for an...