How to clean Xiaomi Redmi Note 9: from cache to complete reset

Xiaomi Redmi Note 9 is one of the most popular smartphones in the budget segment, but even it eventually begins to “brake” due to clogged memory, accumulated garbage and fragmented files. If your device becomes slower, applications suddenly close, and there is less than 10% free space, it’s time to clean up. In this article, we will analyze all the ways from manual cleaning the cache to a complete reset to factory settings, and also tell you how to avoid losing important data.

The Redmi Note 9 (M2003J15SC, M2003J15SS, etc.) is unique in its hybrid memory: 64/128 GB can be extended to microSD, but many users are faced with the fact that the system “forgets” about the memory card or does not transfer applications to it. We will take these nuances into account and show how to clean the smartphone as efficiently as possible without resorting to radical measures.

1.Diagnostics: Why does the Redmi Note 9 need cleaning?

Before you start, it’s important to understand what’s clogging up your Redmi Note 9’s memory.

• 📉 Free space less than 5 GB (the system starts to lag).
• 🐢 Applications are long to open or fly out.
• 🔄 The phone spontaneously reboots.
• 📸 Photos and videos are delayed.
• 🔋 Battery goes down faster than usual (background processes eat resources).

The main “culprits” of memory clogging:

• 🗑️ Application cache – temporary files that should be deleted automatically, but often remain.
• 📁 Residual files after deleting programs (especially games such as the game) PUBG Mobile or Genshin Impact).
• 📷 Duplicate photos/video (for example, after editing in Google Photos).
• 🔄 System updates that are downloaded but not installed.
• 📱 Files. MIUI — log files, error dumps and other service data.

To determine exactly what takes up space, go to Settings → About Phone → Memory. Here you will see the distribution by category: System, Applications, Multimedia, and Other Files. If the Others section is more than 10 GB, that’s a good sign that it’s time to clean.

2. Clear cache and temporary files (without loss of data)

Starting with the safest method, cache deletion, will not affect your personal files, but can free up to 3-7 GB (depending on the number of applications installed).

Method 1: Clearing the cache for individual applications

1. Go to Settings → Applications → Application Management.
2. Select an app (such as YouTube or Facebook).
3. Click Clear Cache (not to be confused with Clear Data – it will delete your account settings!).

Method 2: Mass cleaning of the cache

1. Open Settings → Memory → Cleaning.
2. Click Scan and wait for analysis.
3. Select the category "Cash" and click "Clean".

Method 3: Remove the cache of system applications (for advanced users)

Some system processes (such as MIUI Daemon or Android System) also accumulate cache to clear it.

1. Activate Developer Mode (7 times click on the MIUI version in Settings → About Phone).
2. Back to Settings → Additionally. → For developers.
3. Find the item Do not save actions and turn it on (this will turn off the animation caching).

⚠️ Cache cleaning for Google Play Services or MIUI Security can cause temporary disruptions to Google services or the fingerprint scanner.

3. Removal of unnecessary files and debris

The cache is just the tip of the iceberg, and the main debris is hidden in folders with downloads, duplicates and residual files, and let's look at how to find and delete them.

1. Cleaning the Downloads folder

By default, all files from the Internet, messengers and email are saved to /storage/emulated/0/Download to clear it:

• 📁 Open Explorer (or Google Files).
• 🔍 Go to the Download folder and sort files by date.
• 🗑️ Remove the old ones. APK, archives and documents that are no longer needed.

2. Search and removal of duplicates

Duplicates of photos and videos are often left behind after editing or backup.

• 📷 Use the Files by Google app (Cleanup tab» → «Duplicate»).
• 🔎 Manually check the folders. DCIM, Pictures and WhatsApp Media.

3. Deletion of residual files after uninstallation

When you delete an application through Settings, there are often folders left with data to find.

1. Open Explorer and go to /storage/emulated/0/Android/data.
2. Delete folders with the names of remote applications (for example, com.tencent.ig for PUBG Mobile).

4. Cleaning up the.thumbdata folder

This hidden folder stores thumbnails of images and can weigh up to 1-2 GB.

1. Connect your phone to your PC and enable File Transfer Mode (MTP).
2. Enable the display of hidden files (in Total Commander or Windows Explorer).
3. Find the.thumbdata folders in DCIM and Pictures and delete them.

⚠️ Note: Do not delete the Android folder or MIUI It's going to crash the system, and only delete the files inside if you know what they're for.

💡

Before mass deletion of files, back up important data to Google Drive or PC. Use the built-in Settings → Additional → Backup and Reset feature to do this.

4.Storage optimization: transferring data to a memory card

The Redmi Note 9 supports microSD up to 512GB, but not all files can be transferred to it automatically.

1. Transfer of applications to SD-map

MIUI allows you to transfer only a part of the applications, to check the possibility of:

1. Go to Settings → Applications → Application Management.
2. Select an app (such as Spotify).
3. If there is a button, move to SD-map, press it.

2. Set up file saving by default on SD

To save new photos, videos and downloads to the map:

• 📷 For the camera: Open the camera app → Settings → Preservation site → Memory. SD.
• 📥 For downloads: in Chrome or Files, select Settings → Download folder → SD-map.

3. Forced transfer of files via PC

If MIUI does not allow you to transfer files, do it manually:

1. Connect your phone to your PC and copy folders DCIM, Music or Downloads on SD-map.
2. Remove the originals from internal memory.
3. Create symbolic links (root rights required) or simply use files from the card.

💡

Use Class A2 or UHS-I memory cards – they are optimized for application and reduce lags.

5.Deep cleaning: reset to factory settings

If previous methods didn’t work, and the Redmi Note 9 is still slowing down, the radical way is Hard Reset. It will erase all data completely, so be sure to back up in advance.

Method 1: Resetting through settings

1. Go to Settings → About Phone → Backup and Reset.
2. Select Settings Reset.
3. Mark Clear internal memory (if you want to erase everything, including photos and videos).
4. Confirm the action and wait for the reboot (it will take 5-10 minutes).

Method 2: Reset via Recovery Mode (if the phone is not turned on)

1. Turn off the Redmi Note 9.
2. Press the Power button + Volume up until the MI logo appears.
3. In the Recovery menu, select Wipe Data → Wipe All Data (manage by volume buttons, confirm by power button).
4. After reset, select Reboot.

Method 3: Fastboot Reset (for power users)

If Recovery is not available, you can reset your phone via Fastboot:

fastboot erase userdata


fastboot erase cache




fastboot reboot

You will need a PC with installed drivers. ADB/Fastboot and unlocked loader.

⚠️ Note: After resetting, Redmi Note 9 will require you to enter a Mi Account if you previously activated the “Device Protection” function!

6.Optimization after cleaning: how to prevent memory clogging

To prevent the Redmi Note 9 from getting contaminated again, follow these guidelines:

1.Tune in automatic cleaning

• 🤖 Turn on the settings. → Memory. → Autoclean (deletes unnecessary files once a week).
• 📊 Use Google Files to scan trash regularly.

2. Limit the background activity of applications

• 🔄 Open the Settings. → Battery → Application power management.
• 🚫 Disable auto-run of unnecessary programs (such as games or social networks).

3.Control updates

• 🔄 Turn off automatic app updates on Google Play.
• 📥 Download updates only over Wi-Fi to avoid unnecessary traffic.

4.Use cloud storage

• ☁️ Set up automatic photo upload in Google Photos (Settings) → Backup and synchronization).
• 📁 Transfer rarely used files to Mi Cloud or Yandex Drive.

5. Regularly check your memory

Make a habit once a month:

• 📊 Go to Settings → Memory and analysis of occupied space.
• 🗑️ Delete cache and temporary files.
• 🔍 Check the Download folder for unnecessary files.

💡

If you install/remove games frequently, use the SD-This will reduce the load on the main storage, but the card cannot be removed without formatting.

FAQ: Frequent questions about cleaning Xiaomi Redmi Note 9