anchor.diff:          %% LUMA API Key, must be identical with API Key in external LUMA
           %% service.
           lumaApiKey => {string, optional},
  -        %% The type of storage.
  -        type => {equal, <<"glusterfs">>},
           %% The name of the volume to use as a storage backend.
           volume => string,
           %% The hostname (IP address or FQDN) of GlusterFS volume server.
  
positive.code:         %% LUMA API Key, must be identical with API Key in external LUMA
          %% service.
          lumaApiKey => {string, optional},
          %% The type of storage.
          type => {equal, <<"posix">>},
          %% The absolute path to the directory where the POSIX storage is mounted
          %% on the cluster nodes.
          mountPoint => string,
  
negative.code: -spec s3_model() -> maps:map().
  s3_model() ->
      #{
          %% The type of storage.
          type => {equal, <<"s3">>},
          %% The Id of storage.
          id => {string, optional},
          %% The name of storage.
  