External hard drives consist of a standard hard disk drive and an outer casing with a USB interface, meaning they are susceptible to all the usual hard drive faults, but more, too.
External hard drive, as opposed to internal hard drives, tend to be moved around more, and are more susceptible to physical damage. Our data recovery team see loads of external hard drives that have been knocked, dropped or bumped and suffered from head crashes; this is very likely to happen if the hard drive is dropped when the disk is spinning. The HDD’s read/write heads hover on the tip of the actuator arm a fraction of a millimetre above the spinning magnetic platters. It goes without saying that even a tiny knock can send your drive’s read/write heads crashing onto the platters, potentially causing irreversible data loss. To avoid the possibility of this happening, it is best to keep your external hard drive static while it’s in use.
The USB interface on external hard drives can also cause added issues. Occasionally, upon connection, you won’t be able to see your external hard drive in the ‘Computer’ window on your machine, or it might not autoplay. So what exactly can you do in this situation? Your first port of call should be checking the USB cable that connects your external hard drive to your machine, and also the USB port on the machine itself. Try connecting the external hard drive to another computer, as well as using another USB cable. If you aren’t familiar with the model of external hard drive, make sure it doesn’t require a separate power supply; smaller, more portable external hard drives are powered directly through the USB interface, while larger units require a separate power source to use them. Check if your drive is showing up in Disk Management; if it is, the wrong file system could be in use, there could be a partition problem, or it could be a driver fault.
Disk Manager can be launched on Windows machines by pressing Windows+R and entering devmgmt.msc into the box. This will bring Disk Manager up, and you can browse the program to see if you can find your external hard drive. If there is a yellow exclamation mark next to your external hard drive, it’s a driver fault. This can typically be solved by updating the driver, or uninstalling a reinstalling it. If you’ve ruled out a driver problem, it could potentially be a file system or partition fault. For example, Windows machines can’t read drives that have partitioned with HFS Plus or ext4, which is what Macs and Linux machines use. You’ll need t connect your drive to a machine running one of these operating systems to recover your data.
