Owners of the Xiaomi Redmi 9 smartphone often face a lack of free space, since the basic version of the device is equipped with only 64 GB of internal memory. MIUI operating system and pre-installed applications occupy a significant part of this volume, leaving the user with limited space for photos, videos and games. The solution lies in the possibility of expanding storage, but the standard mode of operation of the flash drive often does not allow you to install applications on it.
There is a proven technical method to integrate an external drive into the system structure, making it an extension of internal storage, a process known as adoptive storage that requires careful attention and understanding of the risks associated with formatting data. In this guide, we will discuss in detail all the nuances of the procedure for your model.
Before you start taking action, you need to realize that after the manipulation, the memory card will be encrypted and tied to this device, and using the same card on another phone or computer without re-formatting will become impossible, since the Android security system blocks unauthorized access to files, so we strongly advise you to back up all important photos and documents in advance.
Requirements for memory card and device preparation
The success of the operation depends on the quality of the drive used. Cheap memory cards with low write speed can lead to serious problems in the smartphone, including interface freezes and long downloads of applications. For Redmi 9, the best choice will be Class 10 or UHS-I cards with a volume of 32 to 128 GB.
The MIUI system has strict requirements for connection stability, so make sure that the battery is at least 60% power before starting the procedure.
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Use the original memory card adapter if you insert it through the adapter, as poor contact can cause a formatting error.
It is also worth checking the status of the memory card slot. If the device has previously used other drives, it is recommended to remove them and make sure that the contacts in the tray are clean. Dust or oxidation can cause a failure when trying to change the type of storage.
Process of formatting and activating function
The first step is to physically install the card into the device slot, and once the smartphone detects a new drive, a message will appear in the notification curtain, but for our purposes, ignore it and go to the deep menu of system settings.
You need to open the Settings section, then select About Phone and find the Warehouse menu. In some versions of MIUI, the path may be different: Settings → Advanced Settings → Memory. In the list of available drives, select your MicroSD card.
☑️ Pre-formatting verification
On the drive control screen, you'll find the option menu, which is usually hidden under three dots or the gear icon in the corner, and you'll select the Format command, and the system will warn you that all data will be deleted, and suggest you choose a use case.
⚠️ Note: After pressing the confirmation button, it will not be possible to return data using the usual methods.
The key to the instruction is to choose the formatting type. The system will offer two options: "Use as portable storage" and "Use as internal storage." You have to choose the second option. If there is no such item explicitly, this may mean that the manufacturer hid this feature in your version of the firmware.
Hidden capabilities of MIUI and ADB teams
Xiaomi Redmi 9 owners often face a situation where the item “Use as internal storage” is not on the menu.This is a limitation of the MIUI software shell, which can be circumvented by debugging via USB and a computer.
To start, activate the developer mode. Go to About Phone and quickly click on the MIUI version seven times. After the message "You became a developer" appears, go back to the main settings menu and find the section Additional → For developers.
Turn on the USB Debugging Toggle. Now connect your smartphone to your computer using a high-quality cable. On your computer, you need to install the ADB (Android Debug Bridge) drivers, which are part of the Platform Tools package.
Where to download ADB tools?
After connecting and confirming the encryption keys on the phone screen, open the command line on the PC in the folder with ADB. Enter the following command to call the storage type selection menu:
adb shell pm set-force-adoptable trueExecuting this command will force the hidden function to activate, and then go back to the storage settings on your phone, select the memory card, and try formatting it again, and the missing menu item should appear.
Comparison of storage modes
Understanding the difference between modes is critical to the proper use of a smartphone, and many users mistakenly assume that the difference is only in the name, but the technical differences are fundamental.
| Parameter | Internal storage | Portable storage |
|---|---|---|
| Encryption | Full encryption, binding to the device | No encryption or FAT32/exFAT |
| Installation of applications | Possible by default | Developer rights only |
| PPC portability | Requires formatting | Direct access to files |
| Speed of operation | Depends on the speed of the card. | Standard reading speed |
Internal storage mode redistributes space for the cache of applications and system files, allowing you to install heavier games and programs that were not previously placed in the phone’s memory.
In portable storage mode, the card is used primarily as a media library, and you can store movies, music and documents there, but the system will try to keep active application data on the built-in memory chip.
Application portability and work optimization
Once formatted successfully, the system can offer to migrate applications already installed, a useful feature that allows you to instantly free up precious gigabytes of internal memory.
However, not all applications support portability, and developers decide whether to move their product to an external medium, and Google's system services and key MIUI components usually remain on the internal drive.
To control movement, go to Settings → Applications → All applications. Select the program you want, press Memory and Change button. If the button is inactive, then the application does not support work from the external drive.
⚠️ Note: Applications ported to the card may load slightly longer than usual, due to the physical limitations of the MicroSD read speed compared to the built-in eMMC memory.
Check the card regularly, and if it is full, it may cause some services to stop working and not take new pictures, and it is recommended that you leave about 10-15% free space for the file system to function properly.
Possible problems and methods of solving them
During operation, there may be situations when the smartphone stops seeing the card or gives out read errors, often due to unstable contact or damage to the file system after improper extraction.
If the device says "damaged" or "required formatting," try restarting the phone, and in some cases, re-enabled USB debugging and computer error checking helps, even though the data will be closed by encryption.
Memory card degradation can be a serious problem, as flash memory has a limited resource of overwriting cycles, and when used as internal storage, wear is faster than with normal file storage.
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If a smartphone is constantly losing a memory card, it may be that its recording class speed is too low to work as a system partition.
In the event of complete loss of access to data, the only options are to reset the phone settings or replace the card with a new one with re-installing applications. It is almost impossible to recover data from an encrypted partition without the original device and keys.