Owners of budget and mid-budget smartphones like the Xiaomi Redmi 9 often face a lack of built-in storage. Android operating system, installed messengers, social networks and a cache of photos gradually fill the available space, which leads to a slowdown in the device. The system begins to warn of memory overflow, and new programs stop being installed.
The solution is to use a microSD card. However, unlike older versions of Android, modern MIUI shells have their own features with external drives. Not all applications can be moved freely, but there are proven optimization methods that will help you win gigabytes of free space.
In this detailed guide, we will take a look at all the nuances of setting up storage on your gadget, you will learn how to format a flash card correctly, how to enable the forced movement of programs and what are the limitations of MIUI 12 or later.
Preparation of memory card and smartphone for work
Before you start moving data, you need to make sure that the external drive is working and correctly installed in the device. Xiaomi Redmi 9 is equipped with a hybrid slot, so it is important to correctly place the SIM card and memory card in the tray. If you use two SIM cards, space for the microSD may not be available without the use of adapters.
Once you physically install the media, the system will automatically prompt it to be set up, and at this point it's critical to choose the right formatting type. If you plan to store only photos and music, select Portable Storage mode. If your goal is to install applications, you'll need Internal Storage mode.
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Use UHS-I (U1 or U3) speed memory cards from proven brands. Cheap, unnamed drives can significantly reduce the speed of the entire smartphone.
The formatting process will clear the map completely, so save important files to your computer or the cloud beforehand. Once the procedure is complete, the system will create the hidden partitions necessary for Android to work correctly with the external drive.
Setting up SD-maps as internal storage
To be able to port applications, you need to turn the memory card into an extension of the internal memory, a process called adaptive storage. Go to the Settings menu → About phone → Storage. Click on your memory card name and select Format.
The system will issue a warning that all data will be deleted. Confirm the action and wait for the process to end. In some versions of the MIUI firmware, the "Use as internal storage" clause may be hidden, in which case the system will prompt you to move the data (photos, media) immediately after formatting.
Why doesn’t the system see the card as an internal memory?
After a successful switch, part of the internal memory will be freed up, and the Android system folder will appear on the map. Now the device considers the external drive as part of the system partition, which allows you to install programs there by default.
How to transfer installed applications to SD-map
When the card is formatted as internal, the transfer process becomes standard, but has its own features in the shell of Xiaomi. Go to Settings → Apps → All applications. Select the program you want to move, for example, a heavy game or a navigator.
In the app menu, look for "Storage." If the map is set up correctly, it will show a "Change" or "Move" button. Click on it and select. SD-The system will start transferring files, progress will be displayed on the screen.
Not all applications support this feature, but app developers may not allow their products to be migrated to external media for security or stability reasons, in which case the move button will be inactive or absent.
☑️ Pre-transfer check
You can use built-in cleanups to mass-transfer data. In the Security app, select Cleanup, then go to file management and sort large files to manually move them to an external medium.
Using Developer Functions for Forced Transfer
If you can't move the program with standard methods, you can use Android's hidden settings. You need to activate the developer mode. Go to Settings. → About the phone and quickly press 7 times on the item "Version" MIUI».
When activated, a new section will appear in the “Additional” menu, “Developers” will appear, and then you will find “Preferred Installation Location” and select “External Drive” and it will make the system try to install all new applications on the memory card.
⚠️ Warning: Forced transfer of system applications or critical services to Google can lead to unstable smartphone performance, cyclical reboots or data loss.
This setting does not guarantee that all applications will be able to work from an external drive. Some components will still remain in internal memory, as this is a requirement of the Android architecture.
Compatibility table of data types for transfer
Not all files and data respond in the same way to movement. Understanding what can be safely transferred and what is best left inside will help avoid errors. Below is a table showing how different types of data behave when migrating.
| Type of data | Possibility of transfer | Impact on speed | Recommendation |
|---|---|---|---|
| Photos and videos | Complete. | Minimum | Move first |
| Cash messengers | Partial | Average. | Clean or transfer manually |
| Games (OBB files) | Complete. | Depends on the card. | Use a quick U3 card |
| System services | Forbidden. | Critical | Leave it in your internal memory. |
As you can see from the table, media files and game cache take up the most space and transfer them the most efficiently, but system components should not be touched, since the speed of reading the internal memory of eMMC or UFS in Redmi 9 is still higher than most memory cards.
Possible problems and ways to solve them
During operation, users may experience card read errors or app shortcuts disappearing, often because the memory card was removed without first turning off the settings menu. Always use the "Extract" function before physically retrieving the tray.
Another common problem is that the interface speed is slow, and if the phone starts to slow down after transferring a lot of applications, then the card writing speed is not enough for modern programs, in which case some of the data will have to be returned to the internal storage.
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The speed of a memory card directly affects the speed of launching applications hosted on it, cheap cards can run 5-10 times slower than internal memory.
Authorization errors may also occur in security-sensitive applications, such as banking clients, who may require re-sign-in or refuse to work if they find their files being moved to an unreliable location.
⚠️ Note: When you reset your smartphone to factory settings, all data on the card formatted as internal storage will be encrypted and become unreadable on other devices without re-binding.
Alternative methods of freeing up space on Redmi 9
If application portability is not possible or does not produce the desired result, you should pay attention to other optimization methods. MIUI has a built-in cleaning function that removes the remnants of deleted programs and temporary files. Regular use of this tool helps keep the system clean.
Use cloud storage, such as Google Photos or Yandex.Disk, with autoload enabled, which will allow you to store original photos and videos online, freeing up local space, and configure sync only over Wi-Fi so that you don't waste mobile traffic.
Another efficient way to do this is to use “light” versions of apps (Lite), such as Facebook Lite or Google Go, which take up significantly less space and consume less resources, which is ideal for budget models like the Redmi 9.