[WORKING MOD] **UPDATE** Swap Internal and External Storage [STILL OPEN 2 DISCUSSION] - Verizon Samsung Galaxy S 4

**UPDATE, Working MOD!**
Mattiadj has a working mod to make your S4's external sd card your internal storage while making your internal just a place for extra resources!
This is HUGE and it is working very well for me. This mod is not a "complete swap" where the two mounting points are just switched but it accomplishes the same goal! There are a few things you will have to get use to once you install this but nothing that can't be overlooked. Here a link to his thread: http://forum.xda-developers.com/showthread.php?t=2468596. I suggest everyone try this out and give him any helpful feedback.
For now, Mattiadj's mod is the closest thing to swapping your storage and will may be the closest we ever get on 4.2.2 (it works great). With Android 4.3 officially coming to our devices soon their may be more possibilities for a "complete swap" on 4.3. Until then, I suggest everyone use mattiadj's mod. Thanks mattiadj!
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Hello S4 owners!
I know I'm not the only S4 user wanting more internal storage on their phone whether it be "16 GB" or "32GB". I've been doing a lot of research into swapping internal with external storage to use the micro sd card as device storage (e.g. 64GB sd card to replace 16GB internal storage vice-versa). I've done this technique on a previous device (http://forum.xda-developers.com/showpost.php?p=43024409) by modifying the vold.fstab file to swap storage mounting points. Since samsung released 4.2.2 on their devices the vold.fstab has been modified without anyone being able to figure out how to swap mounting points. The verizon release of android 4.3 may make modifying the vold.fstab more feasible but we will just have to wait and see.
For now, here are several routes I have looked into:
Modifying vold.fstab: There may be more code we can add but the current file only contains the mounting location for external storage and not internal storage. This makes it seemingly impossible to just swap lines of code. Someone trying to overcome the same road block: http://forum.xda-developers.com/showthread.php?t=2168489.
Modifying storage_list.xml within framework-res.apk: I have looked into how android mounts storage devices and it seems that 4.2.2 and earlier rely on the vold.fstab and storage_list.xml (http://source.android.com/devices/tech/storage/). I then began trying to look into the storage_list.xml located in the framework-res.apk and found these:
http://forum.xda-developers.com/showpost.php?p=27432510
http://forum.xda-developers.com/showpost.php?p=35792201
I tried modifying the storage_list.xml but when I swapped the "sdcard0" and "extSdCard" text in the file (after unpacking adn repacking the apk) my phone went into a bootloop. I understand that swapping two phrases in a file didn't have much evidence to support trying it but I had to find out what it did. Maybe someone can help with this. This example of a storage_list.xml file provided by google (https://android.googlesource.com/de...eworks/base/core/res/res/xml/storage_list.xml) looks much different from the extracted file I pulled which had a lot of random characters and null signs (using notepad++).
Using init.d script: I have found two people who have tried this for the S4:
http://forum.xda-developers.com/showthread.php?t=2363670 This mod results in a lack of access to the internal device storage. (According to the posts)
http://forum.xda-developers.com/showthread.php?t=1772234 This mod results in a successful swap (according to some posts) but is unstable and causes a lot of application crashes and glitches. The OP needs more testers, but the thread is still fairly active and could be a possible route. I have yet to test this.
I understand that there are applications such as forldermount and link2sd that provide options for freeing up internal memory but these options do not provide enough storage for me personally (and others I'm sure). ME7 gave us app2sd ability but that still doesn't relieve enough space. My goal here is to start more discussion to address this issue. Any ideas or comments on the feasibility for swapping storage mounts please post below. DON'T LET THIS THREAD DIE.
Thank You,
MetaMav
P.S. I uploaded my S4's (SCH-I545) vold.fstab if anyone would like to venture at modifying it for this purpose.

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Cool
Sent from my GT-I9505G using XDA Premium 4 mobile app

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Using external as internal would render lag spikes due to garbage collection.

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Performance
previse said:
Using external as internal would render lag spikes due to garbage collection.
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I understand the caveats to swapping storage devices. We do not however fully know how performance impeding the modification will be until we find a fully functioning solution to test. I'm optimistic . My previous device handled swapping very well with not a lot, if any, noticeable performance loss.

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It's a good idea. Wouldn't using something like Link2SD and/or Foldermount help in getting more internal space?

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Correct
maddog00 said:
It's a good idea. Wouldn't using something like Link2SD and/or Foldermount help in getting more internal space?
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You're right, they are fantastic ways of saving space. They do not however provide the ease of having a larger internal storage that everything is installed on by default. Many people also do not want to deal with having to make a link or special exception for every application installed. If I am not mistaken there are also certain app functions that may not work if moved to the external SD card. My goal is that through some discussion and help we can figure out how to make storage swapping available for the S4 like it is for so many other devices.

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MetaMav said:
You're right, they are fantastic ways of saving space. They do not however provide the ease of having a larger internal storage that everything is installed on by default. Many people also do not want to deal with having to make a link or special exception for every application installed. If I am not mistaken there are also certain app functions that may not work if moved to the external SD card. My goal is that through some discussion and help we can figure out how to make storage swapping available for the S4 like it is for so many other devices.
Click to expand...
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But with that slight increase on complexity you get rather significant increases in performance due to the much higher random R/W of the internal storage. Keeping system and most apps on the faster internal is preferable.
You're on XDA man. If the choice is between a slight increase in complexity and a big increase in performance... I'd put my money on performance.
Side: you are very wrong when you say certain app functions won't work. With folder mount there is no difference as far as the app is concerned. These are links not app2sd.
You also don't have to make a link for every app installed. I have it set up to link the entire /Android/OBB/ folder. Set it once and done.
Sent from my SCH-I545 using Tapatalk 4

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Metallice said:
But with that slight increase on complexity you get rather significant increases in performance due to the much higher random R/W of the internal storage. Keeping system and most apps on the faster internal is preferable.
You're on XDA man. If the choice is between a slight increase in complexity and a big increase in performance... I'd put my money on performance.
Side: you are very wrong when you say certain app functions won't work. With folder mount there is no difference as far as the app is concerned. These are links not app2sd.
You also don't have to make a link for every app installed. I have it set up to link the entire /Android/OBB/ folder. Set it once and done.
Sent from my SCH-I545 using Tapatalk 4
Click to expand...
Click to collapse
Thank you for the corrections Metallice. In my previous reply I meant that moving apps via app2sd would prevent certain features from working such as widget functionality and listening for "boot completed" events. I did not mean that using applications such as Link2SD and Folder Mount would cause these complication. Those two apps are very viable solutions for saving space (I use them myself). Also, I understand the concern for performance but I haven't used a device with this mod where I noticed any noticeable performance loss when using applications.
At any rate, I want to use this discussion for making this swapping method work. Any input as far as what I compiled in the OP or possible modifications that could make this mod work on this device would be fantastic.

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Bump
I really enjoyed this mod on my S3. I have tried several methods to accomplish this myself with no success so far. Thanks for starting the OP!!
I hope we can come up with a working solution soon!!!

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Hello and thanks for inviting me to this thread.
I have tried all possibile things I think! I use folder mount now but is really bad as it make my phone slow, hot and battery eater but... Do the job.
Anyway... I have made the switch but I have the problem of duplicates in gallery.
The only way to mount in correct way the external sd card into data/media/0 is with mount -o bind.
I have tried to mount vold file or block file with mount -t vfat umask and all is OK but some media files are not recognized by gallery!!! I can't understand why media files of what's app and of go SMS for example are not seen in gallery!
The only way to fix it is to bind the storage/extSdCard directory but... After we have two mount point for external sd and so duplicates.
Then I have tried another trick which works... So i have changed in vold.fstab the mount point of external sd card in usbDriveA and... Yes all is OK! Bind is OK! Zero duplicates! But.... Always there is a but... Since it is mounted sd USB drive, i have the notification for unmount always visibile and unmounting this became dangerous!
The best way to this swapping is to mount external sd in another folder different from /storage/extSdCard so I can do all I need with init.d script but when I change the mount point in vold.fstab to /storage/extSdCard2 for example, I have bootloop.
Any idea?
From universe with my gs4 snapdragon powered!

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Bump!!
Made it http://forum.xda-developers.com/showthread.php?t=2468596

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mattiadj said:
Bump!!
Made it http://forum.xda-developers.com/showthread.php?t=2468596
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This is AWESOME! I updated the OP.

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jr0324 said:
His thread is very clearly posted in the i9505 sub... has anyone tried this on vzw s4? Aosp/wiz results?
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I have tried this on my VZW S4 SCH-I545 and it works on my device. I think this mod only works for Touchwiz ROMs with init.d support (universal init.d app on the play store may be an alternative) but the OP has yet to receive enough feedback. I do not know if this works for the ocotocore version of the S4 but it should work for any Snapdragon 600 S4 carrier (not confirmed yet). Here are the specs of my device running this mod:
Model: SCH-I545 (Verizon Wireless, Snapdragon 600)
ROM: BoneStock ROM v1.1.4 (http://forum.xda-developers.com/show....php?t=2384362)
Kernel: KTweaker 9/17 build (http://forum.xda-developers.com/show....php?t=2294083)
SD Card: 64GB SanDisk calss 10 (fat32) with a second 10GB fat32 partition for link2sd
Stay tuned for more information on the mod's main thread!

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The init.d support factor would rule this out with ME7 and Safestrap - Rom slots, correct?

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lazer9 said:
The init.d support factor would rule this out with ME7 and Safestrap - Rom slots, correct?
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I'm not sure, but I'd recommend trying the universal init.d app on the store play and see if that works with safe strap.
Sent from my SCH-I545 using xda app-developers app

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MetaMav said:
I'm not sure, but I'd recommend trying the universal init.d app on the store play and see if that works with safe strap.
Sent from my SCH-I545 using xda app-developers app
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I ran the universal init.d app from play store - ran the test - rebooted... Said I already had init.d support. Proceeded with your mod install. But I don't think it's doing anything different. Don't really understand the steps in your OP to verify. I'm using the extfat one.

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lazer9 said:
I ran the universal init.d app from play store - ran the test - rebooted... Said I already had init.d support. Proceeded with your mod install. But I don't think it's doing anything different. Don't really understand the steps in your OP to verify. I'm using the extfat one.
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I've seen posts suggesting exfat may have some issues. I'd try formatting your SD card to fat32 and following the install guide very closely. Let me know if you get it to work or get stuck again. I got it to work with fat32.
Sent from my SCH-I545 using xda app-developers app

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MetaMav said:
I've seen posts suggesting exfat may have some issues. I'd try formatting your SD card to fat32 and following the install guide very closely. Let me know if you get it to work or get stuck again. I got it to work with fat32.
Sent from my SCH-I545 using xda app-developers app
Click to expand...
Click to collapse
I may try that. I assume I could just copy everything to the PC from my ext card then format then copy everything back and give it another go? Is there something I should remove first since I have the extfat one installed now before resorting to flashing the FAT32 one if I go this route?

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lazer9 said:
I may try that. I assume I could just copy everything to the PC from my ext card then format then copy everything back and give it another go? Is there something I should remove first since I have the extfat one installed now before resorting to flashing the FAT32 one if I go this route?
Click to expand...
Click to collapse
You should be able to just copy over to pc and reformat. You need to either remove the init.d script for this mod in your init.d folder before you flash the fat32 one or revert to a previous backup. Read the mod's main thread for details on this.
Sent from my SCH-I545 using xda app-developers app