How to combine SD card and internal memory on Xiaomi

Xiaomi smartphone owners often face a lack of space, especially on entry-level and mid-range models. Even with cloud storage, the device’s local memory is quickly filled with photos, high-resolution video, games and messenger cache. It is at such moments that the need for expanding the gadget’s capabilities, and the most affordable solution is to use a microSD memory card. However, standard Android operation involves using an external drive only as storage for multimedia, which does not solve the problem of lack of space for installing applications.

Fortunately, it is possible to combine the SD card and internal memory, turning the external drive into a full-fledged extension of the system partition. This process, known as Adoptable Storage, allows the system to perceive the card as part of the main storage, which makes it possible to transfer not only files but also heavy programs. In this article, we will discuss in detail how to implement this feature on Xiaomi devices, what risks exist and how to avoid data loss.

Before you start the action, you need to understand that the procedure requires a complete cleaning of the memory card, all the data that was on it before will be irretrievably lost. So backing up important files before starting the procedure is a prerequisite. We will consider both software methods through the engineering menu, and more advanced methods using the computer and the ADB command line, which are relevant for modern versions of MIUI and HyperOS.

What is Adoptable Storage and How Does it Work on MIUI?

The technology that allows you to combine external and internal memory was introduced in Android 6.0 Marshmallow, called Adoptable Storage, the essence of the method is to encrypt the memory card and integrate it into the file system so that the operating system no longer distinguishes whether the data is physically located on the embedded chip or on the external drive, which to the user looks like an increase in the volume of internal storage by the size of the inserted card.

However, smartphone makers, including Xiaomi, often hide this feature in the standard interface, because the speed of budget memory cards can be lower than the speed of the built-in flash memory eMMC or the internal memory of the device. UFS, And that could theoretically slow down the system, but using high-speed maps is a good way to do it. UHS-I or UHS-II Minimizes this risk by making the device stable.

This feature is usually closed on the MIUI shell, but you can get it through special commands or an engineering menu, and it's important to note that once you combine, the memory card becomes attached to a particular device, and you can't just move it to another phone and read the data, because it's encrypted with your smartphone key.

Preparation of memory card and smartphone for the combination

The success of the operation depends on the quality of the drive used. Cheap cards of unknown brands can quickly fail when you write system files intensively or significantly slow down applications. Before starting the procedure, make sure that your card meets the minimum speed requirements.

It is recommended to use cards with a volume of 32 GB to 256 GB. Too small cards will not give a tangible increase, and with very large volumes (more than 512 GB), old models of smartphones can work unstable.

It's also critical to back up all the data on the memory card, and when you combine it, it's formatted, and you can't recover it without a backup, save photos, documents and videos to your computer or to the cloud.

Method 1: Using the CIT Engineering Menu

One of the easiest ways to activate the memory pooling function is through Xiaomi's engineering test menu, which doesn't require a computer connection, but doesn't work on all firmware versions. Open the Phone app and enter a special code to enter the test mode.

In the CIT (Customer Interface Test) menu that opens, you need to find an item associated with internal storage, which can be called "Internal Storage" or "Forced MTBF." Selecting this item can initiate the process of reconfiguring the memory manager. If you have an option on your menu called "Storage reset" or "Format internal", this can trigger the conversion process.

However, on modern versions of MIUI, this method is often blocked or simply changes the mode of operation without real partitioning. If after rebooting, the option “Use as internal” does not appear in the storage settings, you will have to use a more complex but reliable method through ADB.

⚠️ Warning: The engineering menu is designed to test equipment. Don't change settings you don't understand, which can cause sensors or communication modules to malfunction.

Method 2: Combining via ADB (Command Line)

The most versatile method, working on most Xiaomi smartphones with unlocked or even standard debugging mode, USB-cable ADB (Android Debug Bridge: First you need to activate the developer mode on your smartphone.

To do this, go to Settings → About Phone and quickly click on “MIUI Version” seven times. After the message “You became a developer”, go to Settings → Advanced Settings → For developers and turn on “Debugging via USB”. Connect your smartphone to your PC and allow debugging on the device screen.

Open the command prompt on your computer in the ADB folder and enter the command to check the connection:

adb devices

If the device is determined, enter the command to start shell mode:

adb shell

Now you need to find your memory card ID. Type a command.

sm list-disks

You'll see a list of disks, like disk:179.64. Remember this number, it's going to be used for the next step, and that ID is the one that points to the physical media that we're going to convert.

Formatting and setting up the working mode

Once you have the disk ID, you can start formatting it, and the command to put the card into internal storage mode is as follows: Instead of disk:XXX,XX, substitute your ID:

sm partition disk:XXX,XX private

The private option tells the system that the disk must be formatted with some kind of internal storage. The process can take several minutes. Once the command is successfully executed, the smartphone can automatically restart or require manual restart.

Once turned on, the system recognizes the card as part of the internal memory, and in the storage settings, you will see that the volume has increased, and now when you install new applications, the system will default to offer to save them to the combined volume.

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For maximum performance, choose cards labeled A1 or A2, which guarantee minimum random read and write speeds, which are critical for operating system operation and application launch.

If you want to return the card to normal mode (for example, for use in a camera), you will have to use the ADB and command again:

sm partition disk:XXX,XX public

This action will also result in the complete deletion of all data on the media.

Table of comparison of modes of operation of SD card

To better understand the difference between standard usage and combined memory mode, let’s look at the main differences in the table below, which will help you make an informed decision about whether to change configuration.

As you can see from the table, switching to internal storage mode has significant functional benefits, but it limits the mobility of the memory card, so you can no longer quickly transfer a photo to your computer through the card reader without formatting the card.

Also, you should consider the wear of the memory card. The operating system is constantly logging and working with the cache, which creates many write cycles, cheap cards can fail faster than the built-in memory of the smartphone in this mode of operation.

Possible problems and ways to solve them

In the process of combining memory, various errors can occur, most often users encounter a message "Formatting error" or"SD-This can be caused by the file system of the card. Android prefers FAT32 for external drives, but for internal storage mode, the system will create the desired file system (usually ext4 or f2fs).

If ADB fails, check access rights. Some versions of MIUI require root rights to fully access memory manager functions, although standard debugging rights are often enough. Make sure that you have confirmed debugging permission from that computer in the dialog box on your smartphone screen.

Another common problem is the “grid” of settings after the system update. Major MIUI updates or a switch to a new version of Android can reset the partition configuration, in which case the procedure will have to be repeated again, saving the data beforehand.

⚠️ Warning: If after combining memory, the smartphone started to work slowly or applications fly out, perhaps your speed is slow. SD-The card is not enough for system operations, so it's better to return the card to portable storage mode.

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The stability of the smartphone in the mode of combined memory directly depends on the class of speed and quality of the SD-Savings on the drive can lead to interface lags.

Frequently Asked Questions (FAQ)

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Check the status of the memory card periodically, connect it to your computer every six months (backup and temporarily return to public mode if possible, or simply monitor the speed of operation) to diagnose file system errors.

To sum up, combining SD card and internal memory on Xiaomi is a powerful tool to extend the life of a smartphone with a small amount of internal storage. Appropriately choosing a memory card and following the ADB formatting instructions allow you to safely expand the capabilities of the device. However, always be aware of the risks of data loss and the importance of regular backup.