This requires having Cacti and some tool that monitors smart information on disks set up. I use the cvs smartmoncontrol from smartmoncontrol.sourceforge.net
A script I use which pulls some information from smart is here. Note that you need to have read access to the disk device for this to work, so you probably want to use sudo or something to allow the user your webserver runs as (and hence which cacti runs as) to run this script.
This script checks the following information from smartctl: