More and more users are abandoning their mobile in favor of the smartphone. But this underlying trend poses several problems, starting with that of data storage. Inevitably one day or another you will need to connect a hard drive to your smartphone. Do you think it's impossible? We show you the opposite..
How to know if I can use a removable storage unit on my mobile
Before you jump on the first USB cable, you will have to do some checks. We forget it a little quickly but Android is a very different system from Windows. The technical constraints are not the same.
For example, it is very difficult to read data stored on a NTFS formatted hard drive on a mobile phone. In fact, only the FAT 32 is natively managed by Android. Fortunately some manufacturers of smartphones have made the effort to add to their devices a function to read a NTFS partition on Android ..
For those who are not fortunate enough to own one of these devices, there is a simple and effective method to work around this limitation. For this you will need to download the Total Commander file manager and then the Paragon exFAT NTFS USB Android plugin. The latter works in tandem with Total Commander. 
Once these two apps are installed on your mobile, you can read, save or transfer files stored on hard disks in exFat, NTFS, FAT32 and even HFS + (Mac OS) format.
My hard drive refuses to turn on
Another problem, rarely discussed, is that of the power supply to the storage unit. Indeed there are today on the market many models of self-powered external hard drives . They are also acclaimed by the general public for their ease of use..
Light and thin, you can take them everywhere. They are supplied with current directly by the USB connection of PC or Mac. It's more practical and it avoids having to walk around with a power outlet.
Unfortunately the USB ports of smartphones but also of tablets do not deliver enough power to properly power these small hard drives. Results, they simply refuse to start.
Do not panic. There are commercially available small USB hubs also called Hubs powered at 5 volts. You just have to insert it between your hard drive and your mobile. The current supplied by the Hub will power your external hard drive. Obviously this solution requires the use of a power cable. Difficult or even impossible to use in a mobility situation.
Note that there are also Y-shaped USB cables with two USB plugs. This alternative solution consists in powering an external hard drive by connecting it to two USB sockets. Unfortunately this type of accessory has no use on Android.
USB OTG adapter
Last but not least, connection to the removable hard drive requires the purchase of a special adapter called USB OTG. Rest assured, they are quite easily found in shops and at all prices. See the selection of USB OTG cable on Amazon.
You can use this to connect all kinds of peripherals to your smartphone. In addition to a hard drive, you can use it to connect a keyboard, a mouse but also a game controller.
Before you jump on one of the models offered on Amazon, it will be necessary to verify that the USB port of your smartphone is indeed OTG compatible . On some models, it is only used to recharge the battery and cannot be used to connect another device. Take a look at the data sheet. 
If you can't find any information, download the free USB Hosts diagnostics app. You will be able to know if your smartphone is OTG compatible.