If you are using an external hard drive and it gets disconnected from your computer while it is actively transferring information, you may lose those or damage those files. And since you’re a photographer, that means losing pictures you probably can’t replace.
Your hard drive can fall off the table when you move your laptop, it can fall when people walk by and bump the cord, and it’s impossible to find a safe place for it when traveling. The best way to keep it connected is to use double-stick velcro to attach it to your computer. Stick one side to the laptop and one side to the drive and you’re golden. This stuff from B&H is perfect.
Here it is on my laptop on a plane last night (though this isn’t the strip from B&H).
First, put the hard, hook side of the Velcro on the drive and the soft loop side on the computer so that you don’t snag things on your computer when the drive isn’t attached. And watch out for fluffy sweaters with the drive.
Second, use scissors to round the corners of the velcro. This will prevent it from peeling off on the corners and collecting lint and snagging on things.