Chapter 12. Editing a CRUSH Map

To get the CRUSH map for your cluster, execute the following:

ceph osd getcrushmap -o {compiled-crushmap-filename}

ceph osd getcrushmap -o {compiled-crushmap-filename}

Ceph will output (-o) a compiled CRUSH map to the filename you specified. Since the CRUSH map is in a compiled form, you must decompile it first before you can edit it.

To decompile a CRUSH map, execute the following:

crushtool -d {compiled-crushmap-filename} -o {decompiled-crushmap-filename}

crushtool -d {compiled-crushmap-filename} -o {decompiled-crushmap-filename}

Ceph will decompile (-d) the compiled CRUSH map and output (-o) it to the filename you specified.

To compile a CRUSH map, execute the following:

crushtool -c {decompiled-crush-map-filename} -o {compiled-crush-map-filename}

crushtool -c {decompiled-crush-map-filename} -o {compiled-crush-map-filename}

Ceph will store a compiled CRUSH map to the filename you specified.

To set the CRUSH map for your cluster, execute the following:

ceph osd setcrushmap -i  {compiled-crushmap-filename}

ceph osd setcrushmap -i  {compiled-crushmap-filename}

Ceph will input the compiled CRUSH map of the filename you specified as the CRUSH map for the cluster.