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[Q] USB Mass Storage (UMS) on Transformer Prime / Ice Cream Sandwich (ICS)

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By drunken_m, Senior Member on 27th March 2012, 04:51 PM
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Hi!

I know, that this question has been asked many times, so I'll try to formulate it a little different. I know, that Google wants to abandon USB Mass Storage (UMS) with Ice Cream Sandwich (ICS) and focus on MTP / PTP.

This is however a pain in the @ss for most users. Since the Transformer Prime (TF-201) has only 1 partition, which can not be "exported" via UMS - because it has the system on it - would it be possible to modify ICS so, that the internal storage will be partitioned? Let's say 5GB for ICS and Apps, the rest on a separate partition. And the second partition could act like an "SD Card", like it's on most phones?

Would this somehow be possible?

I prefer UMS over MTP/PTP, since the latter 2 are not usable on Linux, and even in Windows Total Commander does not show the MTP/PTP devices (no official support, no plugins that work...) and I'm "forced" to use Windows Explorer
 
 
28th March 2012, 10:34 PM |#2  
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Thats what i though too when i connected my prime to the pc.
Was expecting to connect it in UMS.
29th March 2012, 08:58 AM |#3  
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Usually partitions are defined by the bootloader, so this would need a bootloader edit which nobody really wants to try due to the lack of nvflash access
30th March 2012, 08:11 AM |#4  
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Would it be possible with root?
30th March 2012, 10:45 AM |#5  
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Quote:
Originally Posted by brantje

Would it be possible with root?

No, because UMS would require having an actual "sdcard" partition on the device, and this is not the case. As Diamondback said, to change the partitioning of the storage would require full bootloader access which is not possible without the likes of nvflash.

Personally I think you are better to figure out a way to use the MTP. I use Linux so ?I know what a pain it is, but for the very occasional times I need to access sdcard from my PC MTP works "well enough".
30th March 2012, 11:22 AM |#6  
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Android 4.0 Compatibility Definition at 7.6.2. Application Shared Storage says
Quote:

Regardless of the form of shared storage used, device implementations MUST provide some mechanism to access the contents of shared storage from a host computer, such as USB mass storage (UMS) or Media Transfer Protocol (MTP). Device implementations MAY use USB mass storage, but SHOULD use Media Transfer Protocol.

I read that as saying the method used is down to the developer. I think if mtp was required then the word "MUST" would be used and "SHOULD" is "do this unless there are valid reasons not to do it"
30th March 2012, 03:07 PM |#7  
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Quote:
Originally Posted by peterk-1

Android 4.0 Compatibility Definition at 7.6.2. Application Shared Storage says
I read that as saying the method used is down to the developer. I think if mtp was required then the word "MUST" would be used and "SHOULD" is "do this unless there are valid reasons not to do it"

I don't think it is down to the "developer" as in the ROM chef. Your quote clearly says "Device implementations" - i.e. the way the device is set up. So, a device manufacturer who is creating an ICS device could either configure the device with a separate partition or card for /sdcard and use UMS or they have a single shared partition and use MTP.

The problem with UMS as I understand it is that it requires a dedicated partition, and when that partition is mounted on the host PC, it cannot be accessible to Android (remember all the issues with widgets which were installed on the sdcard on previous android versions not working ?).

The MTP method, on the other hand, does not have this restriction and also allows the dynamic sharing of a single partition between /data and /sdcard which makes much more efficient use of available storage.


So basically this was a design decision which the manufacturer made at design time. In order for a ROM developer to change that, they would need access to be able to split the current /data partition into two chunks: one for /data and one for /sdcard. That capability does not exist with the Prime.

Then again, I could be totally wrong
30th March 2012, 03:46 PM |#8  
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barryflanagan: Quite right in what you say. It's such an easy mistake to type developer instead of manufacturer!!
Cheers
30th March 2012, 05:12 PM |#9  
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Quote:
Originally Posted by Diamondback

Usually partitions are defined by the bootloader, so this would need a bootloader edit which nobody really wants to try due to the lack of nvflash access

Quote:
Originally Posted by barryflanagan

No, because UMS would require having an actual "sdcard" partition on the device, and this is not the case. As Diamondback said, to change the partitioning of the storage would require full bootloader access which is not possible without the likes of nvflash.

Personally I think you are better to figure out a way to use the MTP. I use Linux so ?I know what a pain it is, but for the very occasional times I need to access sdcard from my PC MTP works "well enough".

Hi Guys!

First, thanks for the answers.

Second: "well enough" is not what I would aim for in a high quality and premium device like the TF Prime...

So, if I'm interpreting this right, "we" (the geeks & developers at XDA) need only nvflash for the Prime. That doesn't sound too hard. Personally I don't know nvflash, or how to get it working on the Prime (I'm not a developer), but since we already have root access and an unlocked bootloader it should be no problem.

I ran into the following site after a quick Google search: http://androidroot.mobi/2011/06/13/n...s-transformer/

I think I'm not alone, when I say, that UMS is better than MTP/PTP. Personally I don't care about a shared storage. When I want to copy music or movies to my phone or tablet I'm prefer the UMS method (umount on device, mount on PC).

<rant>On another note, why I dislike MTP: many years ago I had a Creative Zen Touch (20GB), which used MTP. On 2 out of 3 PC's I could not get it work, no matter what I had done, and even the rare times it worked, I could not copy bigger file (I think 1GB or larger) to the device, the transfer always broke up.

After I got the TF Prime, I was really disappointed to see, that ASUS chose this path too (since it's not mandatory, only recommended - I think some ICS Phones have a partitioned internal storage, where 1 partition can act like an SD card). The first thing that happened to me after I got the Prime: I copied a directory from my work notebook on the TF Prime. After some time I deleted that directory (I used the File Manager that came with the device). Then (after the directory was deleted) I connected the Prime to my home PC (the TF Prime was *never* connected to that PC before), and the first thing I saw, was the previously deleted directory - though I did *not* see the directory in the File Manager anymore! So that's why I'm against MTP/PTP. </rant>
30th March 2012, 06:32 PM |#10  
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Quote:
Originally Posted by drunken_m

Hi Guys!

First, thanks for the answers.

Second: "well enough" is not what I would aim for in a high quality and premium device like the TF Prime...

So, if I'm interpreting this right, "we" (the geeks & developers at XDA) need only nvflash for the Prime. That doesn't sound too hard. Personally I don't know nvflash, or how to get it working on the Prime (I'm not a developer), but since we already have root access and an unlocked bootloader it should be no problem.

If only it were that simple. Let me know when you have it ready

As for the whole MTP issue, I agree with you but the reality is it ain't going to change any time soon, at least not in the Prime.

The Galaxy Nexus (Google's own flagship device) I think shows the strategy being pursued, which is not only MTP-only, but also has no storage expansion. What Google, Apple and the rest want is to force us all onto the dreaded Cloud and wean us off local storage all together.

BTW, even on the GNex, I am not aware of any ROMs which have implemented UMS, and that phone IS totally unlocked, unlike the Prime.



Sent from my Galaxy Nexus using Tapatalk 2 Beta-4
27th May 2012, 09:56 PM |#11  
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I've been very frustrated with this issue, but it does make a bit of sense. It sounds like the underlying issue here, going forward, is that what we really need better support across the board. If MTS is going to be the future, it will need to be much more robustly supported on other devices, and we'll need android tools to manage what is available on those devices.

I'm currently looking into other methods of network file access, which will allow me to transfer what I want where I want it, to and from TF201, files of large size and small, with decently high throughput. Running an SFTP server on my tablet looks to be the most likely candidate for what I'm trying to do.
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