My device has 64 GB of internal storage and it's nearly full. I can expand storage with a 256 GB microSD card. However, I don't like that everything stored on the SD card is freely accessible to every app with full storage permission and I would like a way to limit accessibility for at least some folders.

I've read some posts about formatting the SD card as internal storage and that it comes with a significant performance impact. Ideally, I'd like to combine internal storage in such a way that apps and processes run on the phone's internal storage for performance and the SD card is used as internal storage only to store media/documents for the permission system.

Is there a way to do something like that on an unrooted device running on Android 10?

  • actually, that's already the case. apps requires permissions to read from SD Card
    – alecxs
    Jun 27, 2022 at 2:48
  • AFAIK, Android 10 forced scoped storage, that without additional permission, apps can only access their own data and some public folders on external storage.
    – Andrew T.
    Jun 27, 2022 at 3:28
  • @alecxs Yes they require a one time storage permission request and then can access anything. I am looking to limit the permission i.e. app can access Folder A from SD card, but cannot access Folder B from SD card.
    – Cell
    Jun 27, 2022 at 21:54
  • 1
    @AndrewT. Scoped storage was introduced in Android 10 and I have some great apps that use it, but it is not enforced. I'm not a developer, but I believe A10 is lumped with A9 and lower if apps use the "requestLegacyExternalStorage" flag. Apps like photo galleries, video editors, file browsers, etc. populate with all my media with a single permission request. What is not considered a public folder on external storage? I've read that everything is public on SD cards.
    – Cell
    Jun 27, 2022 at 21:59
  • so just deny access on per app base, I am not aware of method on per folder base despites my device is rooted. linux file permissions not working on windows MTP compatible file system (FAT)
    – alecxs
    Jun 28, 2022 at 0:01


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