The size of computers today is amazing. I remember when I bought my first machine several years back, the hard drive was a measly 80 Megabytes. Today they are astronomical compared to those old dinosaurs. The speed, size, and computing power just seems to get better year after year. One shudders when one thinks of how they'll be in ten years or so.
Of course, so has external storage media. Ten years ago, the external hard drive market was very small, with only a few players. Today, however, finding the right back up system for your machine can be particularly troublesome, especially if you aren't familiar with the specific terminology. It's important to know exactly what you want, and exactly what you want it to do before you go shopping. That way you won't end up buying something that's way too much for what you need, or on the other hand, you won't end up buying something that just doesn't have enough juice. When you figure out exactly what you need, you won't be stuck with these common problems.
The first question is how big is your hard drive, and how many computers you will be using this for. If you have only one hard drive that is 100 GB or so, then your needs are minimum, and you could likely get away with a 500 GB back up system. However, if you have multiple computers, you may need some more horsepower. Will you be using your hard drive for data files, music files, photo files, or video files? These take up a varying amount of space, and can impact the bottom line cost you'll be paying for your backup system.
An additional consideration to make is how often you'll be backing up your system. If you are planning on backing it up every day, then that's one thing. If you are only planning on backing it up once a week, or even once a month, as some software recommends, then you might not need such a big backup system. So choose which one you are more likely to use, and that will help you make a purchasing decision.
One more thing to think about is portability. Will you be carrying your backup device around with you? Or will it be sitting in a designated location in your home? Portable models and desktop models are different in size and configuration and portable models are generally more expensive.
With these ideas in mind, you will be much better equipped to choose an appropriate back up system for your machine. Once you are set up and backed up, you won't have any more fear of data loss if your system happens to crash. Happy shopping.