From Fedora Project Wiki

Root_cache Plugin

This plugin cache your buildroots. It create archive of your buildroot and put it inconfig_opts['plugin_conf']['root_cache_opts']['dir'], which is be default "/var/cache/mock/NAME_OF_CHROOT/root_cache/cache.tar.gz". It is enabled by default.


Configuration

This plugin is enabled by default and has the following values built-in:

  config_opts['plugin_conf']['root_cache_enable'] = True
  config_opts['plugin_conf']['root_cache_opts'] = {}
  config_opts['plugin_conf']['root_cache_opts']['age_check'] = True
  config_opts['plugin_conf']['root_cache_opts']['max_age_days'] = 15
  config_opts['plugin_conf']['root_cache_opts']['dir'] = "%(cache_topdir)s/%(root)s/root_cache/"
  config_opts['plugin_conf']['root_cache_opts']['compress_program'] = "pigz"
  config_opts['plugin_conf']['root_cache_opts']['extension'] = ".gz"
  config_opts['plugin_conf']['root_cache_opts']['exclude_dirs'] = ["./proc", \
      "./sys", "./dev", "./tmp/ccache", "./var/cache/yum" ]
  • age_check - if set to True (which is default), then cache date is checked. See option max_age_days bellow. Additionally if some config is newer than cache file, then the cache is invalidated as well.
  • max_age_days - if age_check is True and cache is older than this value, the cache is invalidated.
  • dir - where to put cached files
  • compress_program - which compress program to use. By default pigz is used. If not present, then gzip is used.
  • extension - the cache file is always named as cache.tar$extension. When you use different compress program e.g. bzip2, you should set different extension e.g. ".bz2".
  • exclude_dirs - list of directories, which should not be archived.

You should disable root_cache plugin when using lvm_root plugin - having two caches with the same contents would just slow you down.