What is the best technique for changing the backup location of one's iPhone to an external drive. It would seem that with small SSD's (256GB) and very large iOS devices (128GB) that Apple would easily enable this.
I found the below answer, but asking a non-techie friend to create a sym link is really not ideal.
If you have any number of iOS devices, you likely back your stuff up onto your computer. Perhaps iCloud, but after a certain point, you may have so much stuff to back up that it’s best to just put it all on your computer than it is to pay for the additional iCloud storage. That’s especially the case if you have multiple iOS devices. You can save a lot of space on your drive if you have lots of iOS apps, etc. For instance, we were able to free up 100GB, no joke.
1) Make sure that iTunes is closed.
2) You will now move your folder called ~/Library/Application Support/MobileSync/Backup/ to the drive you want to back up to. For instance, an external drive or secondary drive within your computer. Whichever works for you.
3) Launch Terminal Applications/Utilities/Terminal and type in the following command line:
ln -s /Volumes/DriveName/Backup/ ~/Library/Application\ Support/MobileSync/Backup
In the above example, ‘DriveName’ would be the name of the new backup location.