Connecting a memory card to Xiaomi Redmi 9S: from microSD selection to MIUI settings

Xiaomi Redmi 9S remains a popular choice due to its price-performance balance, but its built-in 32/64 GB of memory quickly ends when used actively. The microSD card solves this problem, but its connection has nuances, from compatibility with the exFAT format to the limitations of MIUI for use as an internal drive. In this article, we will discuss the entire process from card selection to application portability, as well as typical errors that interrupt work with external memory.

It is important to note that Redmi 9S Supports a hybrid slot: either two SIM-card SIM + MicroSD. This means you have to sacrifice a second SIM to expand your memory, and not all cards work equally well with this device — some SanDisk or Samsung models can cause lags when writing files. We tested several options and identified the optimal parameters for stable operation.

Which memory card to choose for Redmi 9S: technical requirements

The manufacturer claims support for microSD up to 512 GB, but in practice with cards with a capacity of 256 GB and above, there may be problems when formatting as internal memory. A1 or A2 (for accelerated application work) with an interface UHS-I (U1 or U3). Here are the key criteria:

• 🔹 Volume: 64–256 GB (128 GB – best price/performance balance)
• 🔹 Speed class: Class 10 or UHS-I U1/U3 (minimum 10 MB/s)
• 🔹 Manufacturer: SanDisk Ultra, Samsung EVO Plus, Kingston Canvas Go! (Performance Checked)
• 🔹 Format: exFAT (for maps) >32 GB) or FAT32 (32GB)

Avoid cards labeled HC (High Capacity) — they may not be correctly identified by the system, and do not recommend using cards from obscure brands: they often have understated real capacity and low write speed, which leads to errors when installing applications. For example, the Transcend 128GB card in tests showed a write speed 30% lower than stated, which caused hangings when copying large files.

Preparation of a memory card before installation

A new microSD card is rarely ready to be used out of the box, and it needs to be formatted, and it should be done before it is installed on the phone, to avoid conflicts with the MIUI file system.

1. Error Check: Connect the card to your PC via a card reader and run the chkdsk X: /f command (where X is the drive letter) in the Windows command prompt.
2. Formatting: In Windows, open "This Computer" → PCM on the map → "Format. Select the file system: 📁 FAT32 — card up to 32 GB 📁 exFAT – for cards from 64 GB (recommended for Redmi) 9S)

Speed check:

CrystalDiskMark

reading

record 10MB/s

If the card has been used on another device (like a camera), be sure to complete the formatting, not fast.This will delete all service files that may conflict with Android. Also remember that after formatting all data will be deleted - make a backup if there are important files on the card.

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If the card is not defined in the phone after formatting, try formatting it in MIUI directly: Settings → Memory → SD card → Format. Sometimes this solves recognition problems.

Installation of memory card in Xiaomi Redmi 9S: step-by-step instructions

At Redmi. 9S memory card slot is combined with SIM-So you have to take the tray out before you install it, either with a paper clip or a special key (included:

1. Tray Removal: Insert the paperclip into the hole on the top of the phone (near the power button). Press until you click, the tray will slide out.
2. Card placement: Put the microSD in the slot face up (contacts should be directed to the back of the phone). SIM-map, set it in the slot. SIM 1.
3. Fix: Carefully push the tray back until the characteristic click. Don't put too much effort into it - it can damage the contacts.

Once installed, the phone will automatically identify the card and suggest you choose a mode of use: portable storage (external memory) or internal memory (extension of the main drive).

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If you choose internal memory, the card will be encrypted and not readable on other devices, a process that is irreversible without full formatting!

Configuring a memory card as an internal drive

Using microSD as internal memory allows you to install applications directly to the card, but has limitations. In MIUI for Redmi 9S, this process looks like this:

1. After installing the card, a notification will appear "New" SD-A map. Put it on him.
2. Select “Configure as internal memory” → “Clean and format”
3. Wait for the formatting to be completed (it can take 5-10 minutes).
4. After the reboot, go to Settings → Memory → SD Card and select “Transfer Data” to move supported applications.

Important: Not all apps can be migrated to a map. System utilities and some games (such as PUBG Mobile or Genshin Impact) remain in internal memory. Also note that the speed of applications from the card will be lower than from the built-in drive, which is noticeable when you start heavy games or multitasking.

If after setting up the card as internal memory, the phone started to brake, try:

• 🔄 Disable the automatic installation of applications on the map in Settings → Annexes → Default location.
• 🗑️ Clear the card cache through Settings → Memory. → Map. SD → Clear the cache.
• 🔧 Return the card to portable storage mode (full formatting is required).

Transferring data and applications to a memory card

Once you have configured the card as an internal memory, you can transfer some of the data to it. MIUI It's done this way:

1. Open Settings → Memory → SD card.
2. Tap "Transfer data" and select files to move (photo, video, audio).
3. For applications: Settings → Applications → Select application → Memory → Change → SD card.

Some files (such as screenshots or downloads from messengers) are saved by default to internal memory.

• 📸 For the camera: Open the camera app → Settings → Preservation site → Map. SD.
• 📥 For downloads: Settings → Annexes → browser → Permits → Memory. → Change the place of conservation.

When transferring applications, keep in mind that:

• 🔹 Some data (such as cache) may remain in internal memory.
• 🔹 Some apps (like WhatsApp) don’t support portability, but allow you to save media files to a map.
• 🔹 After the transfer, the application can run slower – this is normal for memory cards.

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To speed up the application from the map, disable animation in MIUI: Settings → About Phone → MIUI version (tap 7 times to turn on the developer mode), then Additional → For developers → The scale of the animation window (off).

Typical errors and their solution

When working with memory cards in Redmi 9S, users often encounter errors, and here are the most common ways to fix them:

If the card is identified but the files are not copied, check:

• 🔌 Is the card connected in data mode (notifications should have an icon) USB).
• 🛠️ Is there any physical damage to the contacts of the card or slot.
• 🔄 Is the “Data Protection” feature included in the Settings → Confidentiality.

Optimization of memory card in MIUI

To keep the memory card stable, follow these recommendations:

• 🔄 Clean the cache regularly: Go to Settings → Memory. → Map. SD → Clean the cache once a month.
• 📉 Keep at least 10% of the available space for stable work.
• 🔋 Avoid extraction during recording: This could damage the file system.Always use "Safe extraction" in notifications.
• 🛡️ Disable Automatic Backup: The "Backup" function in MIUI It can fill the card with unnecessary copies.

For advanced users: if the card is used as internal memory, but the applications are still slowing down, try disabling MIUI Optimization (requires an unlocked bootloader). This will remove unnecessary background processes, but can affect the stability of the system.

1. Install Magisk and Disable MIUI Optimization module.


2. Reboot the phone.




3. Check the performance through AnTuTu.

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If you use the card as internal memory, don't retrieve it without first transferring the data back to the internal drive, which will result in loss of access to all the applications installed on it!

FAQ: Frequent questions about memory cards in Redmi 9S