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The back of my Samsung Galaxy SIII has a slot for inserting an external memory SD card (MicroSD up to 32 GB) next to the SIM card slot, but I never purchased nor inserted any, just double checked just in case. However when I go to Settings -> More -> Application manager and swipe once to the right the following screen shows up (click to enlarge):

enter image description here

As you can see, it looks as though I've downloaded these applications to an SD Card despite the fact that such SD Card on my system does not exist. Can someone be so kind as to explain what this screen is displaying? Perhaps internal storage and internal memory are both synonymous with internal SD, but I'm not sure and would like clarification. And if this were true, then is this screen displaying applications stored on both the internal as well as the optional external SD card, or just the internal SD card?

Thanks.

Also, what is the gray rectangular area just below USB storage at the bottom of the screen for? My device doesn't have any USB sockets despite the one at the bottom of the device used to recharge the device or transfer files. What is this USB storage? Does the SD card appear as a USB device? Perhaps the external SD card when present appears to the Android OS as a USB device. If not, then what does USB have to do with this screen?

Thanks.


EDIT:

I just checked this information on the Samsung Galaxy S Plus. Here is a screenshot of the breakdown of storage which is broken down among internal phone storage (and personal data which seems to me at least like it's the same thing), internal SD card, and external SD card. So, my guess is that not all phones are the same. This screen was accessed by long-pressing the Home hardware button, clicking on the Task Manager button, and then clicking on Storage.

Samsung Galaxy S Plus storage

As the following screenshots demonstrate, on the Samsung Galaxy SIII the only internal storage present is an internal SD card (which is 16GB as advertised).

Samsung Galaxy SIII Storage Screenshot 1 Samsung Galaxy SIII Storage Screenshot 2

OTOH, on the Samsung Galaxy S Plus, as we have seen there are two separate kinds of internal storage, namely internal phone storage which must be a device-specific format, and internal SD card.

On the Samsung Galaxy S Plus, when one goes to Settings -> Applications -> Manage applications one can see the difference between All and On SD Card. This phone did not have an external SD card at the time the following screenshots were taken, and we can see that only some applications (all of which are user downloads), have been installed on the internal SD card (as opposed to on the other internal memory):

enter image description here enter image description here

The Samsung Galaxy SIII also displays different tabs when one goes to Settings -> More -> Application manager and one can swipe left and right to switch from one tab to another, and the available tabs there are named DOWNLOADED, SD CARD, RUNNING, and ALL. The ALL tab, which includes the applications under DOWNLOADED plus preinstalled apps, however, still contains more applications than can be seen under SD CARD (the SD CARD AFAIK lists applications available in the internal SD card, not sure about external SD). This puzzles me, because I thought that on the Samsung Galaxy SIII the internal SD card was the only available internal storage medium. Screenshots follow:

Samsung Galaxy SIII DOWNLOADED Samsung Galaxy SIII SD CARD

Samsung Galaxy SIII RUNNING Samsung Galaxy SIII ALL

On the Samsung Galaxy S Plus, both applications installed on the internal phone storage location as well as the applications installed on the internal SD storage location when viewed by clicking the application in Settings -> Applications -> Manage applications -> All / On SD card have a button to move the application to external SD storage labeled Move to SD card and since I don't have an external SD card such button returns the message Failed to move application. Not enough memory:

Moving an App from Internal (Phone or SD Card) Storage to External SD Card Storage Move to External SD Card Failed, no external SD card present

The same layout is also available on the analogous screen on the Samsung Galaxy SIII. Here are two screenshots shown when I accessed two applications in the analogous manner by clicking on Settings -> More -> Application manager -> click on any application to view its info`:

Samsung Galaxy SIII Application 1 Information Samsung Galaxy SIII Application 2 Information

On the above screenshots I don't get the difference between the fields Data and SD card data, since what I thought I had understood was that there is only one internal memory location, and I do not have an external SD card on this device. Again the Samsung Galaxy SIII where I tried this had no external SD card. On the screenshot on the lef, the Move to SD card is properly grayed out, which I take it to mean that for some technical reasons the application cannot be moved to the external SD card. On the screenshot on the left, the technical details of the application make it possible to move it to the external SD card, but since no such card is present clicking on the button yields the message Your phone does not have a SD card. Insert SD card..

on the Samsung Galaxy SIII, unlike on the Samsung Galaxy S Plus where clicking the button gives an alert error message.

However, what I find strange on this Samsung Galaxy S Plus is that there does not seem a way to transfer an application from internal phone memory to internal SD card memory (at least not via Android OS's GUI, maybe it is possible if the filesystem is mounted and then files are copied with command-line tools such as Unix cp). After all, the internal phone memory is not read-only as I have installed some applications from Google Play Store there as well. Probably, the excutable .apk files which get installed contain preferential information as to where they want or prefer to be installed once downloaded.


EDIT:

Still, I don't get the USB storage bit (seemingly however empty on the Samsung Galaxy SIII), which shows up on both the Samsung Galaxy SIII and the Samsung Galaxy S Plus, as the above screenshots demonstrate.

As we can see from an above screenshot, on the Samsung Galaxy SIII, no information is given on USB storage (the gray rectangle at the bottom of the Application manager -> SD CARD (USB storage) contains no numbers indicating what percentage of USB storage has been used up). Also from the above screenshots, we can see that the Samsung Galaxy S Plus reports roughly 5GB of internal SD card storage, of which Settings -> Applications -> Manage -> On SD Card reports a breakdown of roughly 400MB used and 4.6GB free from which it seems possible to conclude that on the Samsung Galaxy S Plus USB Storage is synonymous with internal SD card storage, however bizarre that may be.

John Sonderson
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1 Answers1

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Apps shown in the "on SD card" tab aren't actually on the external SD card, they're just apps you are able to move to the SD card. If they'd been on the SD card, the checkbox next to them would've been checked with a colored check mark.

saloalv
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  • It's true. Looks like you're right. Applications shown under Manage applications -> On SD card tab (Samsung Galaxy S Plus) or under Application manager -> SD CARD (Samsung Galaxy SIII) are simply those applications which can be moved to the SD card: they all have their Move to SD card button enabled. Other applications listed under ALL which are not listed in this section are for technical reasons incapable of being moved to an external SD card and (thus) do not appear in this list. Thanks! – John Sonderson Dec 06 '14 at 17:32
  • I still haven't figured out the following: why does the USB storage bar displayed under Manage applications -> On SD card on the Samsung Galaxy S Plus display usage statistics for the internal SD card, while the same section at the bottom of Application manager -> SD card on the Samsung Galaxy SIII tab displays no numeric information? Also, is USB storage on mobile phones always synonymous with internal SD card storage? Thanks. – John Sonderson Dec 06 '14 at 17:36
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    @JohnSonderson the no numerical information I don't know about, since I don't have a Samsung device. It may be a bug, or Samsung designed it that way. Also, USB storage nearly always refers to internal /sdcard/ partition – saloalv Dec 06 '14 at 17:38
  • OK. Thanks. This information is very useful. What about external SD storage, does it also fall under the category USB storage or is it only the internal SD which shows up as such? Could you please post a screenshot of the Application manager -> SD CARD section on your device. I am curious as to what your device says about the USB storage. You can take a screenshot with Power+Home key or Home+Back or swipe your hand across the screen on several devices. Thank you for your information. I really appreciate it. – John Sonderson Dec 06 '14 at 17:42
  • Also, what happens if you mount an external USB drive onto the Android phone (I presume this could also be a possibility if the USB drive had a small enough adapter). Thanks. – John Sonderson Dec 06 '14 at 17:44
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    @JohnSonderson if you mount an USB drive using an USB OTG cable, it will be mounted at /mnt/usbdisk. I don't know what that will be called on the phone though – saloalv Dec 06 '14 at 17:49
  • Thanks, and what about mounting a regular external SD card (by inserting the card, without going through USB cable)? Will that storage also show up as USB storage or not. Where does it get mounted on the filesystem? And would it show up as USB storage in the user interface? Thanks. – John Sonderson Dec 06 '14 at 17:59
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    @JohnSonderson it will show up as external SD card, and IIRC it'll be mounted at /sdcard/external_sd/. I'm not sure of the behaviour if you mount yet another card, via an USB SD card reader though. – saloalv Dec 06 '14 at 18:01
  • Thanks. As to the filesystem I found out from this link that /sdcard is always a symlink to /mnt/sdcard. Samsung Galaxy SIII device there is also a (likely custom) partition called /storage/emulated/0 which is the Home directory of the File Manager application from Cheetah Mobile on Google Play (probably the same as cd ~ at the shell prompt) and after examining its contents this also seems to be a symlink to /mnt/sdcard. On the Samsung Galaxy S Plus /mnt/sdcard is the Home directory of the File Manager app. – John Sonderson Dec 06 '14 at 22:32
  • As to the external storage the Samsung Galaxy S Plus has /sdcard/external_sd and doesn't have /mnt/usbdisk. On the other hand /sdcard/external_sd doesn't exist on my Samsung Galaxy SIII, although this device has six USB directories called /mnt/UsbDrive{A,B,C,D,E,F} and it is presumably these which are used for mounting USB drives via OTG cables. So, my guess is that unless a directory appears in the link I posted, these mount points for the external SD card and OTG USB drives are not standardized and relying on these locations in computer programs is thus unreliable. – John Sonderson Dec 06 '14 at 22:38
  • Also because of these differences, I was not able to conclude whether in the graphical user interface of Android devices, external SD cards and OTG USB drive also fall under USB storage. Please let me know. Thanks. – John Sonderson Dec 06 '14 at 22:40
  • @JohnSonderson Generally, the naming convention of the UI is as follows: /sdcard is USB storage, internal memory is /system, SD card is the external SD – saloalv Dec 06 '14 at 22:41
  • Could you please elaborate on the following: from the GUI it seemed like on my Samsung Galaxy SIII the internal storage was the SD card (I didn't see a separate ROM/internal space). So on such a system the /system directory would also be classed as USB storage. Am I correct? – John Sonderson Dec 06 '14 at 22:49
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    @JohnSonderson /system would most definitely not be classified as USB storage. I think this thread should end, maybe someone could create a chat room. Also, I don't have access to a Samsung device, and my knowledge is only finite – saloalv Dec 06 '14 at 22:51