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Support /mnt/extSdCard screws up various apps. How to fix?

Discussion in 'Android Devices' started by HippoMan, Jun 16, 2012.

  1. HippoMan

    HippoMan Well-Known Member
    Thread Starter

    May 5, 2009
    I purposely purchased a large (32G) sdcard for my Galaxy Tab 2 (10.1), so I can have a lot of extra storage for certain apps.

    However, the external sdcard is named /mnt/extSdCard, while /mnt/sdcard points to a smaller, internal (non-swappable) sdcard that comes with my tablet, and I discovered that a whole slew of apps have been hard-coded to only access /mnt/sdcard as the "external sd card" without the ability to point to any other location, and this cripples my ability to use /mnt/extSdCard as extra-huge storage for some of these apps.

    I've rooted my tablet, so my first thought was to go into a terminal as root and make a symlink from /mnt/extSdCard to some subdirectory of /mnt/sdcard. This would allow all those apps to at least see the contents of the swappable sdcard when they access /mnt/sdcard. However, /mnt/sdcard and /mnt/extSdCard are both FAT32 filesystems on which symlinks are not supported.

    So I thought of another idea, but before I dive in and possibly screw up my tablet beyond repair, I want to bounce it by you folks here, to see what you think about the feasibility of the following procedure ...

    Step 1: back up /mnt/sdcard onto my desktop computer.

    Step 2: back up /mnt/extSdCard onto my desktop computer.

    Step 3: in the directory on my computer where I backed up /mnt/sdcard, copy the entire /mnt/extSdCard contents to a subdirectory called "ext". The full path name would then be /mnt/sdcard/ext, and this subdirectory would contain the entire contents of /mnt/extSdCard.

    Step 4: using adb, or a terminal on my tablet running "su", or something like RootExplorer, change the contents of /etc/fstab (or whatever that file is called under Android), so that the former mount point for /mnt/sdcard is now called /mnt/extra, and so that the former mount point for /mnt/extSdCard is now called /mnt/sdcard. In other words, the new mount point for the swappable card will be /mnt/sdcard, and the new mount point for the internal card will be /mnt/extra.

    Step 5: clear out all of /mnt/sdcard

    Step 6: clear out all of /mnt/extSdCard

    Step 7: run the following commands as root (or whatever similar commands correspond under Android) ...

    umount /mnt/sdcard
    umount /mnt/extSdCard
    mount -av​

    The latter should perform all the mounts in /etc/fstab so that my renamed mounts will go into effect.

    Step 8: restore the backed up /mnt/sdcard contents from my desktop computer to the tablet's new /mnt/sdcard filesystem (including that new "ext" subdirectory)

    Step 9: restart my tablet

    (or perhaps exchange steps 8 and 9)

    If all this works, /mnt/sdcard should now be the large swappable card containing the original internal sdcard contents plus that "ext" subdirectory with the original contents of "extSdCard". Also, /mnt/extra should be the empty internal sdcard, which I can use for whatever I want.

    Aside from the differences between the commands I gave above (standard Unix/Linux) and the Andoid versions of those commands, do you folks think this procedure will work?

    Thanks in advance.


  2. Sandrider

    Sandrider New Member

    Feb 22, 2015
    Did you ever figure this out? I have similar issues now with my s5. What seems confusing to me is that even though symbolic links are not supported on fat32, there is a symbolic link to my extsdcard one level above internal storage in /storage. When I go up that level I have I just left the fat32 partition? It would seem so, except that internal storage will allow me to download and store files over 4gb. (Difficulties getting them out of there) but they appear to be there full size.

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