A lawfirm called today about data recovery of a "backup" drive. A site visit revealed the always fatal "click of death" sound emanating from the drive. It soon became clear this was no backup drive but rather the save point for an ongoing project to scan decades of files. Three years of time scanning wasted plus many of the source files had been destroyed creating a liability problem.
Lesson: In a small office without a server never target an external or portable drive as your primary save point. Save to the computer's built-in hard drive and backup to external drive and/or the cloud. External drives fail at a much higher rate than internal drives. Many designs are prone to overheating from either inadequate passive cooling or from fan failure especially the off brand models. Drives internal to a computer case benefit from strong power supplies and well designed cooling systems. Equally important is to understand that backup means "second copy" of your data. You'll never lose two drives in a short period of time. If a backup drive fails you still have your data at it's primary save point.
Recommendation: At minimum I like to see onsite backup to a secondary hard drive in combination with some form of cloud backup.