External hard drive backups are becoming very popular. The USB or firewire devices offer easy ways to back up your important files, music, and pictures. However, are these external hard drives a reliable solution? Yes, but they will fail over time.
External hard drives are essentially regular desktop hard drives, or laptop hard drives for the smaller ones, with a plastic enclosure around them. So, as true with any hard drive, it has moving, powered parts that will fail eventually. Hard drives 
have an average life of 3-4 years with some drives failing in the first year and others lasting beyond 7 years. That means that you should not hold all your eggs in one basket. In other words, don’t rely just solely on your external hard drive to store your important family pics or business documents.
Since these external hard drives will ultimately fail one day, it is wise to have your files on your computer and to just make a copy of them on your external hard drive. That way, if 
your computer drive or your external hard drive fails, you’ll have a backup on the other one. If your computer cannot store all of your files, then you should consider having a second backup external hard drive where you can store you primary external hard drive’s files. You can copy the files over quarterly or every 6 months and then just turn off the external hard drive when it’s not in use. This will give your backups reliability and longevity. And you will have peace of mind. Also, you will save in the end by avoiding data recovery costs and ensuring your important files are saved.