Combining a memory card with internal storage on Xiaomi Redmi 9A: the complete guide

Why combine memory on Redmi 9A?

Owners of Xiaomi Redmi 9A often face a shortage of internal memory — only 32 GB (of which ~22 GB is available after installing the system). Even after cleaning the cache and removing unnecessary files, the place ends quickly: photos, videos, app updates and games take gigabytes.

This function allows you to use SD-card as part of the main memory of the phone, after the combination:

📁 Applications are automatically installed on the card (if you support the transfer).
📷 Photos and videos are saved to extended storage by default.
🔄 The system distributes files between the internal memory and SD.

But there are nuances: not all cards are suitable, the process is irreversible without resetting, and the speed of work depends on the class. SD. Let’s see how to do it right on Redmi. 9A minimally.

📊 You’ve already tried to combine your memory with Xiaomi?

Yeah, it worked.

Yeah, but there were mistakes.

No, I'm afraid to break something.

I don't know what that is.

Requirements for a memory card for combination

Not every microSD is suitable for memory expansion. Xiaomi Redmi 9A supports microSDXC cards (up to 512 GB), but other parameters are important for stable operation:

Parameter	Minimum requirement	Recommended value
Class speed	Class 10 (10 MB/s)	UHS-I Class 1 (U1) or U3
Capacity	8GB	32–128 GB (optimum for price/performance balance)
File system format	FAT32/exFAT	exFAT (Automatically converted to ext4 when combined)
Brand	Anybody.	SanDisk, Samsung EVO, Kingston (fewer fakes)

⚠️ Note: Class 4 or Class 6 cards cause lags and errors when writing data. If the card already has files, they will have to be deleted - when combined, it is fully formatted into a single file. ext4 (Unreadable on PC without special programs).

You can check the speed of the card through the A1 SD Bench app (available on Google Play), if the write speed is below 10 MB / s, you should not combine the memory - the phone will slow down.

💡

Before buying a card, check it for authenticity with the H2testw utility (Windows). Many AliExpress branded cards turn out to be fakes with low capacity.

Preparing the phone before the merger

Before starting the procedure, follow the mandatory steps to avoid data loss or failures:

Make a backup copy of data (photos, contacts, messages)|Charge your phone at least 50 times%|Remove unnecessary applications and files|Check the memory card for errors (via PC or application) SD Card Tester)|Disable the antivirus (it can block formatting)-->

Pay special attention to backup.

🔄 The memory card will become part of the system and will not be visible as a removable drive on a PC.
📱 Data can only be recovered through Redmi. 9A (Or another phone that supports Adoptable Storage).
🚫 Removing the card without canceling the combination will lead to errors in the application.

⚠️ Note: If the phone has root or custom firmware installed, the unification function may not work properly. In this case, first return the standard software via Fastboot.

Step-by-step: how to combine memory

The process takes 5-10 minutes. Follow the instructions carefully - interruption at any stage can lead to loss of data on the map.

Insert a memory card in the Redmi slot 9A (tray-tray SIM-map).
Go to Settings. → Memory.
Tap your name on it. SD-maps (e.g. SanDisk) 64GB).
In the upper right corner, press three dots (⋮) and select Storage Settings.
Choose Internal Memory (not Portable Storage!).
Read the warning and click Clean and format.
Wait for the process to be completed (the phone will restart 1-2 times).

After the reboot:

📊 A combined section will appear in the Memory menu (for example, Internal Memory: 45 GB).
📲 When installing applications, the system will prompt you to select a storage location (internal memory or storage). SD).

What if the internal memory button is inactive?

If the unification option is not available, the reasons may be: 1. The memory card is too slow (class below Class 10). 2. There are bad sectors on the map (check through CrystalDiskInfo on PC). 3. The phone is running MIUI with limited features (for example, a global version for some regions). 4. The map is formatted to NTFS (you need to reformat to exFAT via PC).

Configuring data retention by default

After the memory is combined, you need to specify where the new files will be stored.

Open Settings → Memory → Storage settings.
Select Save by default.
Set the switch on SD-map: 📸 Photos and videos 🎵 Music and audio files 📄 Downloads from the browser

⚠️ Note: Some apps (such as WhatsApp or Telegram) ignore these settings and store media files in internal memory. SD in the settings of the application.

To transfer existing files:

Connect your phone to your PC via USB (File Transfer Mode).
Copy DCIM, Downloads, Music folders from internal memory to SD.
Remove the originals (if the location is critical).

💡

Combined memory doesn’t increase the performance of the phone — it only adds space for files. Application speeds still depend on the processor and Redmi 9A (2/3GB) RAM.

Frequent problems and their solutions

Even if you follow the instructions correctly, you can get errors. Let's look at the typical cases and how to fix them:

Problem.	Reason.	Decision
Phone doesn't see card after unification	Incorrect formatting or process failure	Remove the card, paste it back, and repeat the procedure. If it doesn't work, format the card on your PC in exFAT and try again.
Applications are not installed on SD	Developer has banned the transfer	Use App Mgr III (from Google Play) to force port or install Lite versions of apps.
Phone brakes after unification	Slow memory card	Replace the card with a UHS-I U3 model (e.g., SanDisk Ultra A1).
There is not enough space, although the SD is combined	System files take up internal memory	Clear the cache in Settings → Apps → All apps → Clear the cache.

If after the combination, the phone began to overheat or discharge quickly, check the card for authenticity - fake drives with low capacity force the system to constantly overwrite data, which increases the load.

adb shell sm list-volumes all

If there is a line in the conclusion mount_point=/mnt/expand/... — If not, the process must be repeated.-->

How to Undo Memory Combination

If you decide to return it (for example, to use the card on another device), follow these steps:

Transfer all important files from the SD to internal memory or PC.
Go to Settings. → Memory. → [Name of name SD-map] → Storage settings.
Select Portable Storage.
Confirm the formatting (the data will be deleted!).