Combine internal and external memory on Android: Adoptable Storage

The problem of lack of gigabytes and the solution from Google

Modern applications require more and more space, and the built-in storage of smartphones often fills up faster than you can notice. Owners of budget and mid-budget devices are constantly faced with notifications that memory is full, which makes it impossible to install new apps or update the system. Fortunately, the platform Android offers a mechanism that allows you to use a memory card microSD not just as a flash drive, but as a full-fledged extension of the main drive.

This technology, known as Adoptable Storagewas introduced back in version Android 6.0 Marshmallow. It allows the system to format the external drive so that it becomes an integral part of the device's internal memory. After this procedure, applications, photos and user data can be written directly to the card, freeing up valuable gigabytes of the built-in chip.

However, the process does not always go smoothly and depends on many factors, including the smartphone model and the quality of the flash card itself. Manufacturers often hide this feature in the settings or completely block it at the firmware level, believing that external drives are too slow for the system to operate. However, with the right approach, you can significantly expand the capabilities of your gadget.

It is important to understand that combining memory is an irreversible action for the data on the card. All files located on it at the time the procedure begins will be permanently deleted. Therefore backup information is a critical first step before any manipulation of disk partitions.

Checking compatibility and preparing equipment

Before you start setting up, you need to make sure that your device physically and software supports the function Adoptable Storage. Not all smartphones, even those running the latest versions, have this option publicly available. Many vendors, such as Android, have this option publicly available. Many vendors such as Samsung or Xiaomi, often disable it in their shells One UI or MIUIto avoid performance problems that may arise when using slow memory cards.

The quality of the memory card plays a role a decisive role in the stability of the system after the merger. If you choose a cheap card with low write speeds, your smartphone interface may experience noticeable lags and apps may take longer to load than usual. It is recommended to use cards of class UHS-I or higher, with marking Class 10 and a data transfer speed of at least 90 MB/s.

⚠️ Attention: Using counterfeit or low-quality memory cards in internal storage mode can lead to data loss and damage to application system files. Make sure that the card was purchased from an official distributor.

To check the real speed of your card, you can use special utilities available in Google Play. If the read and write performance is significantly lower than stated by the manufacturer, it is better to refrain from combining memory and use the card only for media files. It is also worth checking the physical slot: it should secure the card tightly to avoid accidental disconnection while the system is running.

The next step is to prepare the data. Since formatting will destroy all information, copy all important photos, documents and music to your computer or cloud storage. After completing the procedure, it will be almost impossible to regain access to old files without special software, since the file system will be encrypted with the keys of a specific device.

Standard formatting procedure through settings

If your smartphone supports this function at the system level, the process of combining memory will be as simple and intuitive as possible. You do not need to connect to a computer or use third-party apps; all actions are performed directly in the device settings menu. The algorithm may differ slightly depending on the version Android and the manufacturer's shell.

To start the process, insert the memory card into the slot and wait for a notification that it has been detected. Then go to the Settings → Storage (or Memory) section. Select your SD card from the list of available storage devices. In the menu that opens, you need to find the item responsible for changing the type of storage drive.

• 📱 Click on the three dots in the corner of the screen or the menu button to call up additional options.
• 💾 Select item Storage settings or Storage in the map context menu.
• 🔄 Click on the option Format as internal (in some firmware it may be called "Use as internal memory").
• 🗑️ Confirm the warning that all data will be deleted and wait until the process is completed.

The system will offer to transfer existing data to the new drive immediately after formatting. This is a smart move as it instantly frees up space on the onboard chip. You can choose to transfer all apps and media files, or do it selectively later. After the operation is completed, the memory card will be displayed as part of a single amount of internal memory.

If the “Format as internal” item is not present in the settings menu, this means that the manufacturer has blocked this feature. In this case, it will not be possible to combine memory using standard system tools, and you will need to use more complex methods via USB debugging, which will be discussed below.

Activating a hidden function through ADB commands

For advanced users whose devices do not have a format button in the menu, there is a way to activate the function through a computer. This method requires enabling the mode USB debugging and installing drivers ADB (Android Debug Bridge) on the PC. It allows you to send a system command that forcibly turns on the adaptable storage mode.

Before connecting the smartphone to the computer, you must activate the developer menu. To do this, go to Settings → About phone and quickly click 7 times on the item Build number. After the message “You have become a developer” appears, return to the main settings menu, find the new section For developers and activate the switch Debugging via USB.

adb shell sm list-disks

Connect the phone to the computer with a cable and open a command line or terminal in the folder with ADB installed. Enter the command to list available drives. The system will show the ID of your memory card, which usually looks like disk:179,64. Write down these numbers, they will be needed for the next command.

Next you need to run the format command, substituting your disk identifier. Be extremely careful when entering, as an error can lead to formatting the wrong partition.

adb shell sm partition disk:XXX,XX private

After entering the command, a standard system notification about formatting the card will appear on the smartphone screen. The further process is identical to the standard procedure: the system will encrypt the card and offer to transfer the data. This method works on most devices with processors Qualcomm and MediaTekif the function is not blocked at the system kernel level.

Transferring applications and managing data

After successfully combining the memory, the system begins to perceive the card as a single unit with built-in storage. However, this does not mean that all applications will automatically move to the new volume. Control of app placement is left to the user, although some modern versions Android may offer file placement optimization.

To move a specific application, go to Settings → Applications. Select the desired app from the list and open its properties. If the application developer has allowed the transfer, you will see a button Change in the "Storage" section. By clicking on it, you can choose the option to move to the SD card or back to the internal memory.

⚠️ Attention: Not all applications support transferring to an external drive. Developers of widgets, launchers and system utilities often block this feature to ensure stable operation and quick access to data.

The table below shows data types and their behavior after memory merging:

It is worth noting that even when combining memory, the system can prioritize frequently used data on the fast built-in chip, and send less needed files to the card. This behavior is controlled by algorithms Android Runtime and is aimed at maintaining the overall performance of the device.

Restoring factory settings and removing the card

The decision to merge memory is a big step, but the process can be reversed if necessary. If you decide to sell your smartphone, replace the card with a larger one, or simply return the device to its original state, you will need to complete the procedure Format as portable storage. This action will also delete all data on the card.

To do this, go to the storage settings, select your SD card and find the menu item Format as portable (or "Use as portable storage"). The system will warn that all applications installed on the card will stop working and their data will be lost. Confirm the action and wait for the process to complete.

After formatting, the card will again become a regular external drive that can be removed at any time without risk to the system. However, files that were written to it in internal storage mode will remain encrypted and will not be read on other devices or computers without a special decryption key, which is stored only on your phone.

If you plan to use this card on another device, it will need to be completely formatted via a computer into a file system FAT32 or exFAT. This will remove all traces of previous use and make the card universal for reading on any gadget, camera or PC.

Frequently asked questions (FAQ)