[Xiaomi Redmi Note 3 Guides, News, & Discussion] jonaskor:
The Xiaomi Redmi Note 3 is still a very good device and many of us use MIUI as it comes preinstalled and has many advantages. One major disadvantage for many of us is, that it does not support adoptable storage out-of-the-box. This means, that if you have a device with limited storage (e.g. 16GB), you have a problem once you run out of space. Fortunately there is a solution! With these few commands we can activate the adoptable storage feature so we can move apps to SD card and we are back in the game!

This should also work for other phones with Android 6 e.g. Samsung and Sony, that do no support this feature out-of-the-box.

NO ROOT NEEDED! NO FLASHING NEEDED!

Screenshots in the first comment!

What you need

a computer

a phone running Android 6 (or above)

a fast microSD card (at least UHS class 1 recommended)

a backup of all important files (especially from SD card - it’s going to be formatted during the process!)

Step-by-step guide

--- Warning: You are proceeding at your own risk! ---

Enable developer options on your phone (in settings -> about phone -> tap “MIUI Version” 7 times)

Enable „Stay awake“

Enable „USB debugging“

Disable „MIUI optimization“

Download and install „ADB and fastboot“ on your computer

e.g. from here, check back this XDA post for more

Connect your phone via USB

Run a command window (as administrator) and use the following commands

adb shell

sm set-force-adoptable true

sm list-disks

you are going to see a result like disk:179,64

sm partition disk:xxx,xx private/mixed xx

this is reformating your SD card, change xxx,xx according to prior result e.g. 179,64

use private if you want to use the whole SD card as adoptable storage

use mixed xx if you still want a specific percentage of the SD card formatted as “portable” storage e.g. mixed 60 (-> 40 percent adoptable storage)

check success on your phone (setting -> storage)

sm list-volumes

you are going to see a result like private:179,67 mounted fb705131-c6a0-4e3a-959b-605a65334c8c

pm move-primary-storage xxxxxxxxxx-xxxx-xxxxx-xxxxx-xxxxxxxxxx

migrate data to adoptable storage, change xxxxxxxxxx-xxxx-xxxxx-xxxxx-xxxxxxxxxx	according to prior result e.g. fb705131-c6a0-4e3a-959b-605a65334c8c

check process on your phone („Moving data“ in the status bar)

Install „QuickShortcutMaker“ from the Play Store.

Find „com.android.settings“ in Activity-tab

Find „com.android.settings.Applications.ManageApplications“

Create a shortcut for it on your home screen

Reboot!

Use the shortcut to manage apps and move them to the adoptable storage (marked as “external storage”)

Enjoy!

Note:

Not all apps support to be moved!

The system settings won't show the correct storage sizes. Use “Mi File Manager” instead.

All icons of applications stored in the adoptable storage are going to be moved to your home screen after every reboot. You will have to move them back to their folders manually.

In order to install new updates you will have to move the downloaded update file (from downloadad_rom) to your SD card manually and choose it as a source file in the Updater app.

Sources:

http://en.miui.com/forum.php?mod=viewthread&tid=820440

https://xdaforums.com/android/software/auto-formatting-sdcard-to-internal-t3583875

Search: adoptable storage, shared storage, adaptable storage, app2sd, move app to sd card