The documentation regarding clusterpurge.php should be upgraded, due to the fact that the script has a limitation in configurations set in DB cluster mode, with several frontends.

When the clusterpurge.php is run on one of the available frontend servers (e.g. frontend1), it removes content-cache entries from the cluster database and then it also removes local caches in that server. The problem is that when the script is run on another frontend server (e.g. frontend2), it does nothing, because the cache-related entries have already been purged from the cluster's database, and consequently, local caches are not removed from the Frontend2's filesystem.

This is not considered a bug, but rather a product limitation. A workaround for this exists, in for form of the following script:

find /home/site/wrbm/www/var/*/cache/ -atime +5 -name "*.cache" -exec rm -f {} +

This command deletes all cache files (content caches and template-block caches) that have not been accessed for more than 5 days.