su - mysql -s /bin/bash
mysqld_safe --upgrade=MINIMAL --skip-grant-tables --skip-networking
mysql> DROP DATABASE sys;
ERROR 3679 (HY000): Schema directory './sys/' does not exist
mkdir /var/lib/mysql/sys
chown mysql:mysql /var/lib/mysql/sys
mysql> drop database sys;
Query OK, 101 rows affected (0.03 sec)