code: public static void createAllDirectories()
      {
          try
          {
              if (conf.data_file_directories.length == 0)
                  throw new ConfigurationException("At least one DataFileDirectory must be specified");
  
              for (String dataFileDirectory : conf.data_file_directories)
              {
                  FileUtils.createDirectory(dataFileDirectory);
              }
  
              if (conf.commitlog_directory == null)
                  throw new ConfigurationException("commitlog_directory must be specified");
  
              FileUtils.createDirectory(conf.commitlog_directory);
  
              if (conf.saved_caches_directory == null)
                  throw new ConfigurationException("saved_caches_directory must be specified");
  
              FileUtils.createDirectory(conf.saved_caches_directory);
          }
          catch (ConfigurationException e)
          {
              logger.error("Fatal error: {}", e.getMessage());
              System.err.println("Bad configuration; unable to start server");
              System.exit(1);
          }
          catch (FSWriteError e)
          {
              logger.error("Fatal error: {}", e.getMessage());
              System.err.println(e.getCause().getMessage() + "; unable to start server");
              System.exit(1);
          }
      }
docs: Creates all storage-related directories.