basic_archive is an example of an archive module.  This
  module copies completed WAL segment files to the specified directory.  This
  may not be especially useful, but it can serve as a starting point for
  developing your own archive module.  For more information about archive
  modules, see Chapter 49.
 
In order to function, this module must be loaded via archive_library, and archive_mode must be enabled.
basic_archive.archive_directory (string)
     
    The directory where the server should copy WAL segment files. This directory must already exist. The default is an empty string, which effectively halts WAL archiving, but if archive_mode is enabled, the server will accumulate WAL segment files in the expectation that a value will soon be provided.
   These parameters must be set in postgresql.conf.
   Typical usage might be:
  
# postgresql.conf archive_mode = 'on' archive_library = 'basic_archive' basic_archive.archive_directory = '/path/to/archive/directory'
   Server crashes may leave temporary files with the prefix
   archtemp in the archive directory.  It is recommended to
   delete such files before restarting the server after a crash.  It is safe to
   remove such files while the server is running as long as they are unrelated
   to any archiving still in progress, but users should use extra caution when
   doing so.
  
Nathan Bossart