How to Backup an iPhone to an External Drive (step by step and fix errors)

Many laptops with solid-state hard drives have limited space. It becomes more difficult to backup iPhone or iPad to your computer. Now you may backup to your external hard drive. I tried this solution to make a Junction from folder1 to folder 2 (will be explained below) and backed-up successfully.

Steps
1. run iTunes
2. find the folder1 for backup (e.g., \Users\Windowsname\Apple\MobileSync\Backup)
3. turn off iTunes
4. connect an external hard drive and find the disk symbol (e.g., F:)
5. create a folder2 in the external hard drive
6. use command window and the command 'mklink /J "C:\Users\Windowsname\Apple\MobileSync\Backup" "F:\folder2"

There might be an error: mklink error: Cannot create a file when that file already exists

You may check
1. if you run the command as an administrator
2. check if the folders exist

Good luck and thanks for the following websites:

https://smallbusiness.chron.com/backup-iphone-external-drive-72349.html

https://superuser.com/questions/597551/mklink-error-cannot-create-a-file-when-that-file-already-exists