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[Q] How is the storage space on the N5 divided?

OP Ghengis042

10th January 2014, 01:23 PM   |  #1  
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I've owned a Galaxy S2, and a Galaxy S1 (Captivate), both of which had external SD card slots. On these devices, there are various system partitions that share the internal 16GB of storage, used for the operating system, caches, user data, app installation, etc. Part of this is user-accessible as /sdcard, which (I think?) had a fixed size. There was also a fixed amount set aside for application installation. Apps could be moved from the application space to /sdcard, or to /sdcard/external, which was the mount point for the MicroSD slot.

That all made sense to me, though of course it would be nice to be able to designate more or less space for the application partition, or the user partition, or caches, etc, as needed.

On the N5, I don't think it works like that. I saw some posts suggesting that the N5 has multiple mounted filesystems for various tasks as above (system data, app data, installed APKs, caches, user files, etc) but that they are dynamically resized somehow. How does this work? Is it documented somewhere? Do I really need to care, or can I just start installing 1GB+ APKs with abandon? Why do they do this instead of mounting one partition on / and just having sub-directories for /system, /data, etc?
10th January 2014, 01:37 PM   |  #2  
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Quote:
Originally Posted by Ghengis042

I've owned a Galaxy S2, and a Galaxy S1 (Captivate), both of which had external SD card slots. On these devices, there are various system partitions that share the internal 16GB of storage, used for the operating system, caches, user data, app installation, etc. Part of this is user-accessible as /sdcard, which (I think?) had a fixed size. There was also a fixed amount set aside for application installation. Apps could be moved from the application space to /sdcard, or to /sdcard/external, which was the mount point for the MicroSD slot.

That all made sense to me, though of course it would be nice to be able to designate more or less space for the application partition, or the user partition, or caches, etc, as needed.

On the N5, I don't think it works like that. I saw some posts suggesting that the N5 has multiple mounted filesystems for various tasks as above (system data, app data, installed APKs, caches, user files, etc) but that they are dynamically resized somehow. How does this work? Is it documented somewhere? Do I really need to care, or can I just start installing 1GB+ APKs with abandon? Why do they do this instead of mounting one partition on / and just having sub-directories for /system, /data, etc?

http://forum.xda-developers.com/show....php?t=2534010
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10th January 2014, 05:27 PM   |  #3  
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Quote:
Originally Posted by rootSU

http://forum.xda-developers.com/show....php?t=2534010

So, I asked "why don't they just make one partition with sub-directories", and it sounds like to a certain extent that's exactly what happens. It sounds like /data is one physical partition. When you say that /sdcard "points to" /data/media/0, does that mean that it's just a subfolder that's treated specially, and softlinked to /sdcard? Maybe a loopback device that's mounted at /sdcard? If it's the latter, then does some system process quietly resize the virtual filesystem if /sdcard starts to get full? That's the thing I'd like to be able to read more about....
10th January 2014, 05:38 PM   |  #4  
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Quote:
Originally Posted by Ghengis042

So, I asked "why don't they just make one partition with sub-directories", and it sounds like to a certain extent that's exactly what happens. It sounds like /data is one physical partition. When you say that /sdcard "points to" /data/media/0, does that mean that it's just a subfolder that's treated specially, and softlinked to /sdcard? Maybe a loopback device that's mounted at /sdcard? If it's the latter, then does some system process quietly resize the virtual filesystem if /sdcard starts to get full? That's the thing I'd like to be able to read more about....

So to elaborate a little,

/data is a physical partition.

/data/data
/data/app
/data/media

Are all just directories within /data

/data is 11.35 GB on a 16 GB Version so the maximum any directory in /data can be is 11.35 GB. All /data directories combine to make up this total, just like any other /partition/directory structure

The fact that within /data/media is a FUSE file system isn't too relevant to space usage really. Nothing needs resizing. /data/media's free space is the same as /data/app's free space because they're all pulling from the same location as a shared resource. If you put 2 GB in /data/app, that's 2 GB less that can be used in /data/media

Hope that helps

Edit... and yes, /data/media/0 is the mount point for the universally used /sdcard

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Last edited by rootSU; 10th January 2014 at 05:41 PM.
10th January 2014, 06:33 PM   |  #5  
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Quote:
Originally Posted by rootSU

So to elaborate a little,

/data is a physical partition.

/data/data
/data/app
/data/media

Are all just directories within /data

/data is 11.35 GB on a 16 GB Version so the maximum any directory in /data can be is 11.35 GB. All /data directories combine to make up this total, just like any other /partition/directory structure

The fact that within /data/media is a FUSE file system isn't too relevant to space usage really. Nothing needs resizing. /data/media's free space is the same as /data/app's free space because they're all pulling from the same location as a shared resource. If you put 2 GB in /data/app, that's 2 GB less that can be used in /data/media

Hope that helps

Edit... and yes, /data/media/0 is the mount point for the universally used /sdcard

OK, I think I get it. I'd still be interested in seeing what "ls -l /data/media" looks like -- is "0" a *file* or a *directory* or some kind of block-device? I'm just experienced enough at Linux to be intrigued but inexperienced enough not to have dealt with this kind of thing (on a computer) before...
10th January 2014, 08:23 PM   |  #6  
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Here you go...



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10th January 2014, 08:31 PM   |  #7  
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Welp, sure looks like a normal directory to me. I'm guessing that /sdcard is just a plain softlink then? Seems like the right way to do it...
10th January 2014, 08:37 PM   |  #8  
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Yeah its a "mount -o bind"

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