Combining phone memory and microSD card on Xiaomi Redmi 9: the complete guide

Xiaomi Redmi 9 is a popular smartphone with a hybrid memory card slot, but many users face the problem: how to make the system perceive microSD as part of internal storage? In MIUI, this feature is not obvious, and the wrong actions can lead to data loss or slowdown of the device. In this article, we will analyze all the ways to combine memory, from standard settings to hidden firmware capabilities, and evaluate the pros and cons of each method.

It's important to understand that Redmi 9 (codenamed lancelot) runs on MIUI, which limits full memory integration compared to pure Android. However, there are workarounds, from formatting the card as an internal drive to using third-party utilities. We tested all the options on MIUI 12.5 and MIUI 13 firmware so you can choose the best approach without risking data.

Why standard memory combinations don’t work on Redmi 9

Unlike Android One or Pixel devices, where Adoptable Storage is available out of the box, Xiaomi blocks it in MIUI.

• 🔒 Security policy: MIUI It uses its own file system. F2FS internal memory that is incompatible with most microSDs (usually formatted in the FAT32/exFAT).
• 📉 Performance: Class Memory Cards A1/A2 slower than the built-in eMMC memory 5.1 redmi 9, what might slow down the system.
• 🔄 Firmware limitations: B MIUI There is no option “Format as internal memory” in the storage menu, even if the card supports the memory. UHS-I.

However, there are two working methods:

1. Partially merge via MIUI settings (moving individual applications to the map).
2. Complete integration with ADB or third-party utilities (requires root or unlocked bootloader).

⚠️ Note: Once formatted as internal memory, the card cannot be used in other devices without completely erasing the data, and it can lead to accelerated microSD wear due to frequent overwriting of system files.

Method 1: Move applications to a memory card (without root)

The safest way to expand memory is to transfer some applications to a microSD, which is not a complete combination, but will free up to 50% of internal storage.

1. Insert the memory card into the slot (up to 512 GB of UHS-I/U3) is supported.
2. Go to Settings → Applications → Application Management.
3. Select an app (such as Telegram or Spotify) and click Storage.
4. Tap "Change" and select Memory Card (optional only for compatible applications).

Limitations of the method:

• ❌ Not all applications support portability (especially system and games with mobile devices). OBB-file).
• ❌ Application data (cache, settings) remain in internal memory.
• ✅ Suitable for media files: photos, videos and music can be saved to the map by default.

Use a Class A2 or U3 card for speed |

Format the map in exFAT (via PC) |

Create a backup of data on the map |

Check the vacant space (minimum 10 GB)-->

To automatically save photos and videos to the map:

1. Open the camera. → Settings (cogs).
2. Select "Savings place" → Memory map.
3. Restart your phone to apply the changes.

Method 2: Complete integration through ADB (for power users)

If you want to integrate fully (the card becomes part of internal memory), you will need an ADB (Android Debug Bridge) method that works on Redmi 9 with MIUI 12.5+, but has risks:

• 🔧 Requires to activate debugging USB set up ADB-PC drivers.
• 💾 The map will be formatted in ext4 or f2fs — It will not be read on other devices.
• ⚡ Lags are possible when using slow cards (class below) A2).

Step-by-step:

1. Connect your phone to your PC via USB (File Transfer Mode).
2. Open the Command Prompt (Windows) or Terminal (macOS/Linux) and type:

adb shell


sm list-disks

You'll see a card ID, like disk:179.64. Copy it and do:

sm partition disk:179,64 private

Once you reboot, the card will become part of your internal memory.

sm partition disk:179,64 public

⚠️ Warning: If the phone starts to brake after the combination, check the card speed with AndroBench. 10 MB/s, The card is not suitable for such operations.

Comparison of methods of combining memory

For most Redmi 9 users, the first method (application portability) is optimal. If you want full integration, use ADB, but only with UHS-I/U3 cards (for example, Samsung EVO Plus or SanDisk Extreme).

Transfer applications in settings |

ADB-Teams for full integration|

Third-party utilities (Link2SD, App2SD) |

I haven’t tried anything, just the standard use of the card.|

Mistakes and decisions in memory consolidation

When working with memory on Redmi 9 users often face the following problems:

• 🚫 "Failed to move the application": the reason - the application does not support external storage or the card is formatted in the "Space" NTFS (need exFAT).
• 🔄 "Memory card not found": Check the slot (on Redmi 9 it is hybrid - if the second inserted SIM, The card won't work).
• 🐢 "Phone brakes after unification": Wine slow card (class below) A1) or fragmentation of the file system.

Decisions:

• 🔧 For transfer error: use App2SD (requires root) or transfer only the application cache through Settings → Warehouse → Kesh.
• 🔄 If the card is not readable: restart your phone or format it via PC in exFAT.
• 🛠️ For brakes: disable the unification through ADB (sm partition disk:ID public and use the card only for media files.

💡

Before combining memory, check the card's real speed with AndroBench. If the Random Write is below 5 MB/s, the card is not suitable for installing applications.

How to bring it all back: the cancellation of the union

If you have problems after the merger, you can cancel the changes in two ways:

1. By ADB (if you used sm partition):

adb shell


sm list-disks




sm partition disk:179,64 public

Replace 179.64 with your card ID.

1. Through MIUI settings (if you have transferred applications):

Go to Settings → Applications, select the transferred application and click “Move to internal memory”.

After the cancellation of the merger:

• The card will be removable again (can be retrieved without losing data).
• Applications installed on the map may stop working – they need to be reinstalled.
• Files saved to the map (photos, videos) will remain intact.

⚠️ Note: If you format the card as an internal ADB, It won't be read on a PC without a special utilities like DiskInternals Linux Reader, and you'll have to format it again to be reused on other devices.

Best memory cards for Redmi 9: recommendations for choosing

The speed of the card depends on how comfortable the phone will work after the combination. For Redmi 9, cards with the following characteristics are suitable:

Top.-3 maps 9:

1. Samsung EVO Plus U3 (128 GB) – the best price/quality ratio, read speed up to 100 MB/s.
2. SanDisk Extreme A2 (256 GB) – Optimized for applications, Class A2.
3. Kingston Canvas Go! Plus (64 GB) is a budget version with UHS-I support.

Avoid no-name brand cards – they often have understated real-world features and can fail when used intensively.

💡

Even the fastest memory card will be slower than the built-in eMMC. Only combine memory if internal storage is critically lacking and you are ready for possible brakes.

FAQ: Frequent questions about memory pooling on Redmi 9