With apologies for my naivete:
I want, insofar as possible, to periodically back up the data on my non-rooted Samsung Galaxy S8. To this end I do two things:
1) I periodically do adb backups with the command
adb backup -all -apk -shared -f backupfile
2) I mount my phone as a network drive on my Windows machine, where I use robocopy to maintain mirrors of the directories /sdcard and /storage/0000-0000. These mirrors are updated nightly via a script containing the commands
robocopy z:\sdcard d:\phone /s /z /zb /mir /xx /xo /fft /r:0 /w:0 /min:10
robocopy z:\storage\0000-0000 d:\phone /s /z /zb /mir /xx /xo /xd mp3s /fft /r:0 /w:0 /min:10
Thanks to Izzy's very helpful answer here, I am aware that some apps store data in directories such as /data/data that are not accessible to me without root access, and also that some apps might have opted out of making their data accessible to the adb backup.
Question 1: To clarify: Is the adb backup (at least potentially) capturing at least some data beyond what I'm able to capture in my mirrors?
Question 2: Is the adb backup restricted to data that has been created by apps? For example, if I've manually copied a file from my computer to my phone's SD card, is that file included in the adb backup?
Question 3: Does any of the above strike you as insane, and if so, what strategy would be saner (short of rooting, which I prefer to avoid)?