Learning Ceph - Second Edition

Customizing CRUSH

In this section, we will cover steps on how to tailor a CRUSH map to reflect local topology and requirements. Ceph provides us two ways to update a cluster's CRUSH map. One is to extract the current CRUSH map in binary form, decompile it to text, edit the file like any other, then compile and re-inject. In many cases though, with recent Ceph versions we can use subcommands of the familiar ceph utility including ceph osd crush to make changes in a safer and far more convenient way. In this section, we will demonstrate both methods.

For this exercise, we will again practice on the sandbox cluster used earlier in this chapter. If you do not have a sandbox Ceph cluster running, please refer to Chapter 5, Deploying a Virtual ...