code: def create_pool(service, name, replicas=3, pg_num=None):
      
      if pool_exists(service, name):
          log("Ceph pool {} already exists, skipping creation".format(name),
              level=WARNING)
          return
  
      if not pg_num:
          # Calculate the number of placement groups based
          # on upstream recommended best practices.
          osds = get_osds(service)
          if osds:
              pg_num = (len(osds) * 100 // replicas)
          else:
              # NOTE(james-page): Default to 200 for older ceph versions
              # which don't support OSD query from cli
              pg_num = 200
  
      cmd = ['ceph', '--id', service, 'osd', 'pool', 'create', name, str(pg_num)]
      check_call(cmd)
  
      update_pool(service, name, settings={'size': str(replicas)})
docs: Create a new RADOS pool.