A lot of users now back up data to an external hard disk drive. Whether you accidentally delete a file or have a full system crash, backing up your data to a local hard drive is probably a good idea. Your operating system is likely to have utilities to make this easier, or you may be using third party disaster recovery software which backs up an image to your external hard drive. Either way, this will not protect you if your hard drive is stolen!
Most users place much more value on their data. Hardware is normally insured and you can get replacements easily. However, you simply cannot replace your data and files. Typically when a theft steals a computer, they will simply unplug everything and leg it! Any hardware worth taking will be stolen, but the thief is not going to hang around. He is not interested in anything of low value that is going to be hassle to swipe!
Hence, one of the best ways to protect your external hard drive is simply to hide it! Do not sit it on top of your desk or CPU where it will be a target. Use a two meter cable and place it at the back of a draw or somewhere well out of site (preferably where it cannot be knocked!). We can talk about encryption and tracking software, but to be honest – once the hard drive is gone, you are unlikely to see it again. Where hard drives have been hidden, in almost all instances the drive has been left behind. Cables have been unplugged or cut, but rarely has a thief bothered themselves with what essentially has no intrinsic value for them!