How to completely clean memory on Xiaomi 9: from cache to system files

Xiaomi 9 even a few years after the release remains a popular smartphone, but its 64 or 128 GB of memory have the unpleasant property of filling up with “nothing is known”. Photos, instant messengers, app updates and system debris eat up precious gigabytes, and the user suddenly sees a notification: “Memory is full.” In this article, we will analyze all possible ways to clean up memory – from safe (cache removal) to radical (reset to factory settings), and also tell you how to avoid repeated memory clogging due to hidden functions. MIUI.

It's important to understand that just deleting files through Gallery or Files is not enough. The main memory eaters are hiding in system folders, app cache and duplicate media files. We analyzed user reports and tests on Xiaomi 9 (codenamed cepheus) and identified 5 key methods that have the maximum effect.

1. Diagnostics: what exactly takes up memory on Xiaomi 9

Before you clean, you need to understand which files are taking up space. MIUI There's a built-in memory analyzer, but it often shows data inaccurately:

1. Through Settings: Go to Settings → The phone. → Memory. This shows categories like "Applications," "Images," "Video," etc. Click on each to see the details.
2. Files: Open the Files app (folder icon), go to Analysis, and you can see the file types, including the hidden ones.
3. Third-party tools: install DiskUsage or Files by Google from the Play Market, which will show the exact size of folders, including system folders (for example, the file size, /data/app or /Android/obb).

Typical “culprits” of memory clogging on Xiaomi 9:

• 📸 Duplicates of photo / video (created when editing in the Gallery or automatic backup).
• 🎮 Cash games (daddy) /Android/obb weigh 10+ GB).
• 🗑️ Messaging garbage (Telegram, WhatsApp download media in the background).
• 🔄 Remnants of Remote Applications (Folders) /data/data They are not always completely cleaned).
• 📱 System dumps (.dmp or.log files in) /sdcard/MIUI/debug_log).

If the System section is more than 15 to 20 GB, that's a cause for concern, perhaps temporary update files or faulty logs have accumulated, and deleting them requires super-user rights, but more on that later.

2. Cleaning up app cache and system debris

The safest and fastest way to free up 1 to 5 GB is to remove the cache. Cache speeds up applications, but grows into uncontrollable sizes over time. On Xiaomi 9, it can be cleaned in three ways:

Manual cleaning of cache for individual applications

1. Open Settings → Applications → Application Management.
2. Select an app (such as YouTube or Facebook).
3. Press Warehouse. → Clear the cache.

For games (e.g, PUBG Mobile or Genshin Impact cache can weigh several gigabytes. Delete it only if the game starts to slow down, otherwise it will download data again the next time it runs.

Mass cleaning of cache of all applications

To avoid cleaning each application individually:

1. Go to Settings → Memory → Cleanup.
2. Click Clear Cache (usually frees 500MB-2GB).
3. For deep cleaning, choose Deep cleaning (remove unnecessary ones). APK, post-expenditure).

Close all active applications

Connect charging (the process can take 5-10 minutes)

Check the free space before and after cleaning.

Do not clear the cache of system applications (e.g. com.android.systemui)

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Cleaning of garbage through “Safety”

V MIUI There is a built-in security tool (shield icon):

1. Open the Security app.
2. Go to the Cleanup section.
3. Press the check and wait for the analysis.
4. Select the categories to clean (we recommend marking everything except Download).

This method removes:

• 🗑️ Temporary files (.tmp,.temp).
• 📁 Empty folders.
• 🔍 Remains of the remote APK.
• 📋 Logs of system errors.

⚠️ Note: Do not clear the cache of com.miui.home and com.android.phone applications – this can lead to interface failures or network loss.

3. Delete unnecessary files and duplicates

Even if you regularly delete photos from the Gallery, the Xiaomi 9 still has:

• 📸 Hidden folders (.thumbnails, DCIM/.thumbs).
• 🎥 Videos in low resolution (created when sent via messengers).
• 📄 Duplicate documents (e.g. screenshots with the same content).

To find and remove them:

3.1. Search for duplicates through the "Files"

1. Open the Files app.
2. Go to the Analysis section → Duplicate.
3. Select unnecessary copies and click Delete.

Manual cleaning of hidden folders

Use a file manager with access to hidden files (such as Solid Explorer or Solid Explorer) FX File Explorer):

/sdcard/DCIM/.thumbnails – photo miniatures (can be deleted)


/sdcard/MIUI/debug_log - Error Logs (Delete)




/sdcard/Android/obb – cache of games (delete if games are not used)




/sdcard/Download – Old downloads (check and clear)

Cleaning of messengers

Telegram, WhatsApp and Viber automatically download media files to make room:

• 📥 In Telegram: Settings → Data and memory → Clear the cache.
• 💬 On WhatsApp: Settings → Warehouse → Storage management (sorting by size).
• 🎵 In Viber: Settings → Media → Clear media files.

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In Telegram, turn off autoload media: Settings → Data and memory → Autoboot media → Select Never, and this will prevent the photo/video from automatically downloading in the background.

4. Transfer data to a memory card or cloud

If the internal memory is full and you don’t want to delete anything, transfer the files to an external medium. Xiaomi 9 supports microSD up to 256 GB (in a hybrid slot), as well as cloud services.

Transfer of annexes to SD-map

Not all apps support portability, but it’s worth trying:

1. Go to Settings → Applications → Application Management.
2. Select an app (such as Spotify or Google Maps).
3. Click Warehouse → Change → Memory Map.

Limitations:

• ❌ System applications cannot be moved.
• ❌ Some games (such as Call of Duty Mobile) block the transfer.
• ⚠️ After the transfer, the application may work slower.

4.2 Use of the memory card as internal storage

Adoptable Storage allows you to combine microSD with internal memory.

1. Put the memory card in.
2. When a notification appears, select Use as internal storage.
3. Follow the instructions (the map will be formatted!).

⚠️ Note: After that, the card cannot be retrieved without losing data, and it will also run slower than the internal memory (especially if the class is not the same). SDHC Class 10 or lower).

Automatic booting to the cloud

Set up automatic backup of photos and videos:

• 🌥️ Google Photos: Settings → Backup and synchronization (free up to 15 GB).
• 🌍 Mi Cloud: Settings → Xiaomi account → Mi Cloud → Gallery (5GB free).
• 📦 Yandex Disk: Settings → Autoboot (10GB for free).

5. Radical methods: reset to factory settings

If nothing works, and if there's not enough space, you'll have to reset completely, and that will remove everything, including:

• 📱 Annexes and their data.
• 📸 Photos, videos, music (if not saved in the cloud).
• 📋 System settings (Wi-Fi, wallpaper, accounts).

How to do the reset correctly:

1. Save important data: copy your photos to your PC or cloud, export your contacts (Contacts) → Settings → Exports).
2. Disable your Xiaomi account (Settings) → Xiaomi account → Get out).
3. Go to Settings → About Phone → Resetting → Erase all data.
4. Confirm the action (you will need to enter a pattern lock or PIN).

After discharge:

• 🔄 The phone will reboot and return to the “out of the box” state».
• 📱 When first switched on, follow the instructions of the setup wizard.
• 🔒 Do not restore backup from Mi Cloud if it is old – it will bring back the garbage.

⚠️ Note: On Xiaomi 9 with unlocked bootloader, a reset can result in a device lock (Anti-Rollback). → The phone. → Version. MIUI (Press 7 times on "Core»).

6.Prevention: How to prevent memory clogging

To avoid cleaning up your memory every week, set up the Xiaomi 9 correctly:

6.1. disable automatic media downloading

Messengers and social media are the main memory eaters.

• 📸 Instagram: Settings → Account. → Multimedia settings → Save the originals (disable).
• 💬 VK: Settings → General. → Save media files (disable).
• 🎵 TickTok: Settings → Data and memory → Cash (clean once a week).

6.2. Cache restriction for individual applications

Some apps (like Google Play Services or Facebook) can take up gigabytes of cache.

1. Go to Settings → Applications → Application Management.
2. Select the application → Warehouse.
3. Click Cache Limit (if the option is available).

Set-up of automatic cleaning

V MIUI There is an automatic cleaning function:

1. Open Security. → Cleanup.
2. Activate Auto Cleanup.
3. Select the frequency (we recommend weekly).

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Regularly cleaning the cache and disabling autoload media can save up to 30% of memory on Xiaomi 9 without deleting important files.

7. Advanced methods (for experienced users)

If the standard methods don't work, and the memory is still filled with "nothing you know what," it's time to use advanced tools that require superuser rights or work with the user. ADB.

7.1 Cleaning through ADB (rootless)

With help. ADB You can remove system debris that is not available through the interface:

1. Install ADB on PC (instruction: official website).
2. Connect Xiaomi 9 to USB And turn on the debugging. USB (Settings → The phone. → Version. MIUI → Press 7 times, then return to Additional → For developers).
3. Follow the commands: adb shell pm clear com.miui.cleanmaster MIUI adb shell rm -rf /sdcard/MIUI/debug_log — deletion of adb shell rm logs -rf /sdcard/Download/*.Apk – Removing old ones APK

7.2. Remove unnecessary system applications (root required)

Many pre-installed apps (Mi Video, Mi Music, Browser) cannot be removed without root.

1. Install Root Explorer or Titanium Backup.
2. Go to /system/app or /system/priv-app.
3. Remove folders of unnecessary applications (for example, MiuiVideo, MiuiBrowser).

List of safe to remove system applications:

• 🎬 com.miui.video - standard video player.
• 🎵 com.miui.player - Music player.
• 🌐 com.android.browser – the standard browser.
• 📖 com.miui.notes – notes (if not used).

⚠️ Warning: Removing system applications may cause malfunctions MIUI. Before deleting, create a backup copy through TWRP Or OrangeFox Recovery.

7.3. Optimization of the file system

Over time, the file system F2FS (Xiaomi 9 is fragmented, which slows down and increases the space occupied:

1. Install SD Maid (root required).
2. Launch SystemCleaner → CorpseFinder (will delete the remnants of deleted files).
3. Run Defrag (if available for your file system).

FAQ: Frequent questions about Xiaomi memory cleaning 9