MySQL 5.1 upgrades will be performed on your servers on Sunday March 29th at 10:00pm CST. The maintenance should last a few hours with sites only being unavailable for a period of 45 minutes to one hour while our webserver recompiles. While we will have backups of all your databases prior to these upgrades it would be prudent that any critical data be backed up on your own just in case. I would also recommend that over that night any e-commerce sites be placed into 'maintenance' mode in order to avoid a rare 'lost order'.