CRUSH map internals
To know what is inside a CRUSH map, and for easy editing, we need to extract and decompile it to convert it into a human-readable form. The following diagram illustrates this process:
The change to the Ceph cluster by the CRUSH map is dynamic, that is, once the new CRUSH map is injected into the Ceph cluster, all the changes will come into effect immediately, on the fly.
How to do it...
We will now take a look at the CRUSH map of our Ceph cluster:
- Extract the CRUSH map from any of the monitor nodes:
# ceph osd getcrushmap -o crushmap_compiled_file- Once you have the CRUSH map, decompile it to convert it into a human-readable/editable form:
# crushtool -d crushmap_compiled_file
-o crushmap_decompiled_fileAt this point, the output file, crushmap_decompiled_file, can be viewed/edited in your favorite editor. In the next recipe, we will learn how to perform changes to the CRUSH map.
3. Once the changes are done, you should compile these changes...
