And thanks to this technology, not always but usually the HDD will automatically notify the users if something bad is going to happen to the HDD in the near future thus giving a reasonable amount of time for the owner to make backups.
There are several ways you can run SMART tests manually in Linux, but if you don't prefer command-line classical GNU Linux utilities, then there is an excellent, simple, yet a powerful GUI called GSmartControl (which is basically a GUI front-end for a CLI app actually).
You can run these tests without having to be afraid of any data loss, because there won't be any!. It is a safe, standard troubleshooting mechanism which almost all the modern HDDs support.
*. Automatically highlights errors or unusual "activities".
*. Enable/Disable automatic "light-weight" tests on your data without slowing down the HDD.
*. Display advanced drive details (BIOS data, temperatures, etc).
*. Multiple device support.
*. Basic and advanced tests, etc.
This is officially supported by Ubuntu so you can easily install it using the "software center". But for those of you who prefer the command-line/Terminal... just enter the below command to install GSmartControl in Ubuntu.
sudo apt-get install gsmartcontrol