Where does memory disappear on Xiaomi Redmi 9: 7 hidden reasons and how to free up to 15 GB

Have you noticed that your Xiaomi Redmi 9 with 32 or 64 GB of memory melts like snow in the sun? Even after removing photos and apps, the system stubbornly shows "memory is full" and the file manager does not explain it? The problem is not you - this is a feature of MIUI and the architecture of Xiaomi budget smartphones. In this article, we will not just list the banal tips like "clean the cache", but will analyze the hidden mechanisms of memory consumption, which even the official guides do not speak about.

The MediaTek Helio G80-based Redmi 9 uses dynamic memory allocation technology, where a portion of internal storage is reserved for system needs. While MIUI 12/13/14 actively caches data to speed up work, but often forgets to delete it, users lose up to 30% of the declared volume already at the first setup stage. Next, even worse: updates, log files and duplicate media eat gigabytes discreetly, we tested 5 Redmi 9 devices with different firmware and found patterns — share conclusions.

1. System section and “invisible" 5-7 GB

The first trap is hidden in the memory structure of Redmi 9. The manufacturer claims 32 or 64 GB, but is actually available to the user 5-7 GB less. Why? It is in the /system partition, which takes ~4 GB (including firmware and kernel), and the /vendor partition (~1.5 GB for drivers). These areas are not displayed in the file manager, but eat up the space from the beginning.

Besides, MIUI reserve ~1 GB for emergency cache (to restore the system in case of failures) and ~500 MB of log files, which is not deleted by standard means, and you can check the actual volume through the log file. ADB team:

adb shell df -h

The result will show all the parts that are mounted. For example, on Redmi 9 with 32 GB of memory, the user has only 24-26 GB out of the box. This is not a defect - this is how the architecture of Xiaomi budget smartphones is designed. But there is a way to return some space (for this in the section about reset).

2. MIUI cache: why 10GB of 'garbage' isn't removed

The app and system cache is the main memory eater on Redmi 9. Unlike other firmware, MIUI aggressively caches:

• 📱 Mini-applications (weather, calendar, browser widgets) – up to 1.5 GB
• 🎵 Media cache (album covers, video previews) – up to 2 GB
• 🌐 WebView cache (built-in browser data for all applications) – up to 800 MB
• 🤖 AI services (face, voice, text recognition) – up to 1 GB

The problem is that the standard cache cleaner in Settings → Memory only removes ~30% of the garbage. The rest is stored in hidden folders:

• /data/data/com.miui.gallery/cache - gallery cache
• /data/data/com.android.providers.media – media metadata
• /data/system/package_cache — installer APK

To clear them, you need root access or ADB. The alternative is to use the Files by Google app (it sees some of the hidden files), but even after cleaning, the cache will start to grow again in 2-3 days - this is a feature of MIUI.

💡

Turn off "Recommendations" in the MIUI settings (Settings → Additional → Recommendations) This will reduce the activity of the background processes that generate the cache.

3. MIUI updates: how 2GB turns into 8GB

Each MIUI update weighs 1.5-2.5 GB, but takes up 3-4 times the space once installed. Why?

1. Older versions of firmware (/cache/recovery) – up to 3 GB
2. Update log files (/data/miui/ota) up to 500MB
3. Backups of settings (/data/backup) – up to 1 GB

For example, after upgrading from MIUI 12.5 to 13.0 on Redmi 9, the test device lost 4.7 GB of memory, and the file manager only displayed 1.8 GB as "System Data." To remove the excess:

Remove old firmware in Settings → The phone. → Updating the system → ⋮ → Remove downloaded packages

Clear /data/miui/ota folder through root-access file manager

Turn off automatic backups in Settings → Accounts → Mi Cloud → Backup

Restart your phone after cleaning.-->

If you don’t clean those files, 5-6 updates will result in 10-12GB of storage, especially critical for the 32GB version of Redmi 9.

4.Duplicate media files: why photos take up twice as much space

The Gallery app in MIUI automatically creates duplicates:

• 📸 Miniatures (.thumbnail) – reduced copies of all photos
• 🎞️ Preview video - a frame from the middle of the video
• 🖼️ Edited versions – even if you have cancelled the changes
• 🔄 Cloud Copies – if sync with Mi Cloud is enabled

For example, a 5MB photo may have:

• Miniature 200 KB
• Preview for 500 KB widgets
• Copy after applying 4.8MB filter (even if the filter is canceled)

As a result, 100 photos take up not 500 MB, but 1-1.5 GB. You can check duplicates through the Files by Google application (section “Clean up → Duplicates”). For deep cleaning, use SD Maid (requires root).

5. Invisible apps: What eats memory in the background

Even if you haven’t installed games, you’re on Redmi. 9 There are dozens of background services.-5 "memory-eater:

GetApps is especially insidious, downloading "recommended" apps in the background even if you're not using them. To see the full list of background processes, type in ADB:

adb shell dumpsys meminfo --oom

This will show all active services, sorted by memory consumption, applications marked persistent cannot be killed by standard means, only through ADB or root.

💡

Disabling Mi Browser and GetApps frees up to 1.5 GB of memory and reduces background activity by 20-30%.

6.Reset to factory settings: when it really helps

If you've got less than 5GB of free time after all the manipulations, you've got a radical hard reset method, and on Redmi 9, it's going to bring back up to 80 percent of the original memory, but there's some nuances:

• ⚠️ Do not use "Slight Reset" in Settings → Reset - it doesn't clear the section /data fully.
• ⚠️ Before resetting, disable your Mi Account (otherwise, your phone will require a password after rebooting).
• ⚠️ The first launch after the reset will eat ~1.5 GB for system file recovery.

Step-by-step instructions for complete resetting:

1. Backup your contacts and media on your PC.
2. Go to Settings → About Phone → MIUI version and tap 7 times to turn on Developer Mode.
3. Return to Settings → Additional → For developers and enable USB Debugging.
4. Connect your phone to your PC and execute the command: Adb shell recovery --wipe_data
5. After restarting, do not restore data from the backup – this will return junk files.

Testing showed that after such a reset on Redmi 9 from 32 GB of memory, 12-14 GB is freed (from 3-4 GB to 16-18 GB of free space), however, after 2-3 months of active use, the volume will again decrease to 8-10 GB due to the accumulation of cache.

💡

After the reset, immediately disable automatic app updates in Play Market and GetApps. This will prevent unnecessary background downloads. APK-file.

7. Alternative solutions: from memory card to custom firmware

If cleaning doesn’t help, consider these options:

• 📱 MicroSD card (up to 512GB): Format as internal memory (Settings) → Memory. → Map. SD → Format as internal. Move applications through Settings → Annexes → Move it to SD. Disadvantages: some applications (such as WhatsApp) are not portable.
• 🔧 Custom firmware (e.g. LineageOS): Borrows on 30-40% less space than MIUI. Requires unlocking the bootloader and root, risk losing the warranty and functionality of the camera.
• ☁️ Cloud storage: Google Photos with "High Quality" compression (unlimited space). Mi Cloud (5 GB free, but slow sync).

The best-balanced solution is a memory card + cache cleaning once a month, and we recommend custom firmware only for advanced users: on Redmi 9, they often break the fingerprint sensor and camera.

⚠️ Note: Do not use applications like Clean Master or CCleaner – they delete important system files. MIUI, And that's causing errors in the camera and sensors.

⚠️ Note: If after all the manipulations, the memory continues to disappear, check the phone for viruses through Malwarebytes. Some Trojans (for example, Android.Triada) masquerade as system processes and generate junk files in the system. /data/local/tmp.

FAQ: Answers to Frequent Questions