Cacti, as of version 1.0.1, requires access to the MySQL time zone database. You will see the following error at initial setup or during the upgrade process if you are required to perform this:

ERROR: Your Cacti database login account does not have access to the MySQL TimeZone database. Please provide the Cacti database account “select” access to the “time_zone_name” table in the “mysql” database, and populate MySQL’s TimeZone information before proceeding.

To accomplish this, do the following:

/usr/local/bin/mysql -u root -p mysql < /usr/local/share/mysql/mysql_test_data_timezone.sql 

Once that is done, login to MySQL and run the following:

GRANT SELECT ON mysql. time_zone_name TO 'cacti'@'localhost' IDENTIFIED BY 'password';
flush privileges;

That's all.