Even with new devices featuring 16+ GB of internal storage, users still manage to run into problems with there not being enough space for applications and other things. Although this is usually only a problem that older devices face due to their small internal storage, it’s also possible on newer devices as well. Thankfully, a solution has already been crafted for the Samsung Galaxy S III.
The method, called ExtSd2InternalSd, helps users overcome this problem by effectively swapping the internal and external SD cards so that users can user the internal SD for applications only. As XDA Senior Member mattiadj explains:
My aim so became to use the external sd as internal sd and internal sd ONLY for apps installation so became used as internal memory!
And… yes after a while i have to make this working!!! So now my 64gb external sd is used for all tasks which the internal sd was used and the internal sd is only used for apps storage!! All extra files (resources, caches, etc etc) are stored in my external SD!!
Also if i want to see the internal memory management i can see that now my phone has 64gb internal memory and 16gb external!!
As described, the method essentially switches the internal and external SD cards so that the external is mounted as the internal and vice versa. It is not an overly complicated process. Users are directed to format their external SD card to FAT32 with their computer and then flash an update.zip to automatically switch mounts for you. After that, simply reboot, and enjoy up to 64 GB of internal storage and 16 GB of external storage.
To learn more, head over to the original thread._________