External hard drives are failure prone because people believe because they are seperate from the computer that you can handle them while they are spinning or they are tougher but in reality they are often the same harddisk as in your pc just mounted in case with a usb interface and power supply. Last winter I bought a 4tb external drive, ripped it apart and mounted it in my pc. Why? Because it was the EXACT model as the bare drive, just $50 cheaper. They also get dropped, exposed to liquids, kids and the environment and age, if they sit for a long time they can fail. I only use externals to transfer data. I've got a box of destroyed externals from people wanting me to fix them. There are really only two ways to store data long term, and before the cloud only one. Physical removable media. I'm sure my 3.5, 5.25 and 8 inch disks are still readable if I only had a pc capable of running the hardware without massive amounts of backdating or finding a motherboard that still has IDE and ISA slots. Goto Newegg, get a bluray or dvd burner, I'm sure you can find a USB one, a spindle of blanks, less than 70 bucks total. There is great little program that I use that is totally free, burns everything from cds to blurays across several different brand of burners. And people say home burned optical media doesn't have good shelf life, but that is total b.s. I have cds I burned in the early 90's when the tech first came out that will read today. I store them in dark closet, in cases to prevent scratches. This is the ONLY way to securely back up your data save the cloud. I've got years of training and decades of experience and I had to find simple, reliable ways to backup data for people who were technically declined. My mother learned how to back up her data, my brother knows how to also but in his case he's just stubborn so he uses the cloud now.