Recent Android versions (5 and above), as you probably have noticed, do not allow you to mount SD Card / storage partition as USB Mass Storage (UMS) when plugging it to a computer (or any other machine for that matter).
The reasons Android acts like so are varied, ranging from UMS being prone to crash third-party apps to Microsoft has patents on FAT filesystem.
Without getting into the technicalities of why exactly Google chose to remove UMS support from Android, here’s how you may regain it, granted you own a rooted device and you want to mount an external SD Card.
Note: it also works for internal SD Cards if the STORAGE partition is separated from the SYSTEM partition.
Enable UMS On Android
Currently, there are a few apps offering to restore the lost UMS option, nevertheless, I found the following to be the most simple and reliable of them all:
USB MASS STORAGE Enabler
The steps to run UMS Enabler are simple. Before you install the app, make sure you’ve enabled installation from ‘Unknown sources’ found under Security inside Settings.
Also, make sure you give the app full root permissions when it asks for it, otherwise, it’ll be useless.
- Download UMS Enabler from here: UMS Enabler
- Connect your device using USB cable to your computer.
- Open the ‘UMS Enabler’ app and press ‘Enable Mass Storage’. Remember, give the app root access if it asks.
At this point, you might get various messages by the app, for instance, there a message asking you to set SELinux – a Linux module Android uses to make it more secure – to permissive state; this is required for the app to run properly.
Another message you might get, if you’re like me and have re-partitioned your Android, it may complain about not finding the device memory card but finding an alternative partition block instead.
Read these messages carefully and decide judiciously.
When you’re done using UMS Enabler, before disconnecting the USB cable, use eject option from the computer and then press ‘Disconnect Mass Storage’ inside the app.
If you’ve disabled SELinux upon using UMS Enabler. Before exiting the app, it’s highly recommended that you turn the option back on. SELinux helps keeping your Android safe and secure. To re-enable it, tap the app’s menu button and then select ‘Enable SELinux and Exit’.