Getting the CRUSH map
Getting the CRUSH map is the necessary first step in editing the map.
To get the CRUSH map for your cluster, run the following:
Syntax
ceph osd getcrushmap -o COMPILED_CRUSHMAP_FILENAME
Ceph will output (-o) a compiled CRUSH map to the file name you specified. Since the CRUSH map is in a compiled form, you must decompile it first before you can edit it.