I love exFAT supported external micro SD card on Samsung Galaxy S III. I can enjoy movie video that more than 4GB file size finally. However, Samsung Galaxy S3 does not support USB mass storage mode natively. Android 4.0 Ice Cream Sandwich seems to disable USB mass storage feature. Latest Samsung Galaxy S2 ICS firmware does not have this feature too. But worry no more, there is an application called SGS3 Easy UMS can help to enable USB mass storage on Samsung Galaxy S3. It will make external micro SD card on Samsung Galaxy S3 available as USB mass storage device. It supports exFAT for the moment (tried FAT32 but not working). Come on, try it out. Don’t stick on Media device (MTP) and Camera (PTP) mode only. Note – root access is required.

Did not root Samsung Galaxy S3 yet? Please follow this guide to do so ~ How to root Samsung Galaxy S3 with CF-Root? (Video)
Download SGS3 Easy UMS here.
After running the app, the two generic drive letters show up under My Computer but clicking on them gives error message like, “Please insert a disk into drive E”.
Any ideas, please?
Internal USB storage is known not working. Do you have external micro SD card in your phone?
Yes. I have micro SD card in my phone. Connected my SGS3 to laptops, one is running XP and the other one running Vista and they both give the same error message. Waiting for your reply. Thanks.
Is it using exFAT file format?
Thanks for pointing it out. My card was FAT. Since I’m not aware of a tool to covert FAT to exFAT format, I copied my card data to HD, formatted it to exFAT and re-copied the data. Now it is working. Thank you so much! I would like to buy you a beer: do you accept credit cards?
Just thanks will do.
Update: it only worked yesterday after I reformatted the card. Today, back to baseline i.e. two drives show up but are not accessible. I have tried rebooting my laptops and SGS3 but no change.
Hi SK, you need to execute this program whenever you rebooted your phone.
Yes. I executed it after rebooting. The only difference is that for the first time, I had reformatted a smaller 128MB card just to see if exFAT works and it did. So, I posted a message here. The second day, I reformatted my current 8GB card and re-copied files. It works fine in my mobile phone and read/writes files via card reader but won’t work when my mobile is connected to my computer via cable i.e. the drives show up in file explorer after executing the program but are not accessible.
Sorry SK, I have no idea then. You might want to consult SGS3 Easy UMS Developer at XDA website.
you rock. worked wonderfully. thanks for solving my headache. as a linux user, this was the only negative for this phone.
Hi.
Will this app be able to connect the SGS3 to my USB car hifi?
That’s why i need the usb mass storage.
thanks!
If your car Hi-Fi supports exFAT, then yes.
It doesn’t … -.-
Thank’s anyway!
Great apk Jayce, thanks for the advice.
Is there any ways for enabling USB mass storage on INTERNAL memory WITHOUT need of root access?
I don’t think so.
Comes up as a cd rom drive.. I may have a fat32 formatted card.. hmm.
is there any way to put the internal storage to a ums mode ??
I don’t think so, ahmed.
I am having trouble using this App. IT will connect to the PC, but when I drag and drop a file it will say “This Disk is write-protected” How do I get past this? Thanks in advance!
You have this issue on internal storage or external SD card?
It is the external SD Card
Hmm… It should work. Try on other PC see.
Just download the drivers and connect your phone again to your computer http://www.samsung.com/us/support/owners/product/SGH-I747MBBATT