Hello,
I’m new to much of this. I want to flash Android M to my Nexus 4 but I am heeding many people’s warnings to backup my device. However, nothing I’ve tried has allowed me to do so. In my searches, I discovered this thread that enables OTG flash drive support for Nexus 4 phones:
http://forum.xda-developers.com/show…1&postcount=48
But when I installed it over the stock TWRP 3.0.2.0, it showed an external slot with 0MB and would not allow me to select it. I’ve tried various flash drives, all formatted to FAT 32, I’ve tried a powered external USB 3.0 drive enclosure (NTFS formatted) – nothing works. The cable I’m using is not a "Y" cable, which is why I tried using my external backup drive, which is powered but NTFS. Is that the issue?
I’m new to much of this. I want to flash Android M to my Nexus 4 but I am heeding many people’s warnings to backup my device. However, nothing I’ve tried has allowed me to do so. In my searches, I discovered this thread that enables OTG flash drive support for Nexus 4 phones:
http://forum.xda-developers.com/show…1&postcount=48
But when I installed it over the stock TWRP 3.0.2.0, it showed an external slot with 0MB and would not allow me to select it. I’ve tried various flash drives, all formatted to FAT 32, I’ve tried a powered external USB 3.0 drive enclosure (NTFS formatted) – nothing works. The cable I’m using is not a "Y" cable, which is why I tried using my external backup drive, which is powered but NTFS. Is that the issue?
Finally I decided, to heck with it, I’ll just create a nandroid backup to my phone’s storage and then drag it onto my PC, but it only has 4.5GB free space left. I could go and uninstall most of my apps, but what is the point of backing it up then? I need almost 9GB of space on a device that has just 16GB.
This crap is so frustrating. I expect installing Marshmallow would be hard, but I did not expect a backup, which should be a simple operation, to be so challenging 
Any help would be greatly appreciated.