How to Back Up and Sync Your Android Phone Directly to an External Hard Drive

howtogeek.com:

Cloud storage makes backing up data from a phone a seamless experience for most people. However, from privacy concerns to internet speed requirements, there are reasons to prefer a local backup. The cool thing is you don't even need to connect to a PC to do it—just use a hard drive.

While it's technically easy to copy files over to an external drive manually, that's a tedious way to back up data. Fortunately, there's an Android app that can sync the folders on your phone to an external drive for you. We'll show you how to use an app called FolderSync.

What Hardware Do You Need?

Let's get all of our equipment in order first. You're going to need an external drive and a way to connect that drive to your phone.

If you're using a USB-C flash drive or an external SSD with a USB-C to USB-C cable, then you don't need to look for anything extra. Simply connect the drive to your phone. You can even use an external NVMe drive.

If you're dealing with a drive without USB-C, then you need a USB hub or smartphone docking station with the necessary ports. It will serve as the middleman between your phone and the drive.

What Data Can You Back Up?

Any files that are accessible in your phone's internal storage through the file manager are fair game. That includes any photos or screenshots you've captured on your device, plus anything in your Downloads folder. Then there are the files you may have organized yourself, like the contents of your Documents folder or the songs you've stored in Music. I have folders for eBooks and comics that I keep backed up as well.

Some aspects of your office are trickier. You can't tell your contacts app to sync to a hard drive automatically, but you can export your contacts to a VCF file and make a copy. Your call logs and text messages are less accessible, but you can create a local backup using the SMS Backup & Restore app. You can also back up your calendars by exporting them as ICS files.

Unfortunately, data that you need to export manually