Finally finished, without errors, but no change... I still have the following files:
-rw------- 1 root root 20G May 24 13:05 /var/www/vhosts/system/<domain>/logs/access_log.webstat
-rw------- 1 root root 20G May 24 10:27 /var/www/vhosts/<domain>/logs/access_log.webstat
.. is it a problem that...