keystone.conf [cache] enabled is not enabled.
Caching greatly improves the performance of keystone, and it is highly recommended that you enable it.
Caching is not completely configured.
Although caching is enabled in keystone.conf [cache] enabled, the default backend is still set to the no-op backend. Instead, configure keystone to point to a real caching backend like memcached.
Memcached isn’t reachable.
Caching is enabled and the keystone.conf [cache] backend option is configured but one or more Memcached servers are not reachable or marked as dead. Please ensure keystone.conf [cache] memcache_servers is configured properly.