The disk drive is designed to vent excess heat through the aluminum shell, which can and should become warm to the touch. The temperature should be about 20c above ambient temperature on use, and the disk itself is within its operating temperature to 60c. You can check the operating temperature using a SMART diagnostic utility.

Modern disks drives have a diagnostic on board processor that monitors the disk during operation and records various diagnostic values including any detected failures. This diagostic method, S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology; often written as SMART) is a monitoring system for computer hard disk drives to detect and report on various indicators of reliability, in the hope of anticipating failures. For more information about SMART and its values, please see http://en.wikipedia.org/wiki/S.M.A.R.T.

SMART data can be accessed and used for active testing using a SMART diagnostic program. There are numerous SMART monitoring tools available- we recommend the following:

Smartmontools (All Platforms): http://smartmontools.sourceforge.net/ (Requires OSX-SAT SMART driver for use on MacOS, available here:https://github.com/RJVB/OS-X-SAT-SMART-Driver)
HDDScan (Windows ) http://hddscan.com/
SMARTreporter (Mac) http://www.corecode.at/smartreporter/