# TODO be user-friendly
  $ osdmaptool --help
   usage: [--print] [--createsimple <numosd> [--clobber] [--pg_bits <bitsperosd>]] <mapfilename>
     --export-crush <file>   write osdmap's crush map to <file>
     --import-crush <file>   replace osdmap's crush map with <file>
     --test-map-pg <pgid>    map a pgid to osds
     --test-map-object <objectname> [--pool <poolid>] map an object to osds
  [1]
