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HOW TO - 64GB exFAT SDXC card ruined by Cyanogenmod - how to get data back

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By satanxda, Junior Member on 26th July 2012, 01:25 PM
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I am writing this n00b friendly howto for anybody who will encounter similar problem that I had, since I couldn't find much info how to solve it on this forum.

Recently I have flashed CM9 and later CM10 preview on my Galaxy S3 I9300 with 64 GB Sandisk SDXC card. The card was formatted in Samsung stock ROM, so naturally, it was formatted as exFAT. CM9 and CM10 reported it as "damaged SD card", but this was expected, since open source AOSP ROMs do not support exFAT. However, when restored to original stock ROM via CWM recovery, the stock ROM was showing "damaged SD card" error, too! Not sure why this has happened - the only info I found was someone mentioning that "CM9 is known to do this on exFAT cards" on this forum.

Connecting the card (via adapter and card reader) to computer didn't help - it showed as a RAW partition, Windows was asking to format it and even reported incorrect size. Trying about 7 different open source and commercial recovery tools did not help. However, if booted to recovery mode, CWM could see the card just perfectly!

So this is how to get the data back:

1. Boot to CWM recovery mode (power off the phone, then hold Volume Up-Home-Power buttons for 5 sec)

2. When in CWM recovery mode, connect phone via USB to computer. The phone should be recognized and drivers installed (if not already).

Note: I had problems with Windows recognizing the phone in recovery mode on some PCs (only 1 out of 3 worked, actually). To solve this, installed drivers from Samsung Galaxy S3 Toolkit (first step after toolkit installation) and problem gone: http://forum.xda-developers.com/show....php?t=1703488

3. Run adb command (from Android SDK platform tools) to ensure that the phone is visible to operating system - it should show serial number of the device and "recovery" next to it:
adb.exe devices

4. Browse the phone to find the location of sdcard (mine was /sdcard):
adb.exe shell

Note: when first time connected to phone via "adb.exe shell", running "ls" in /sdcard directory came out empty. Had to "exit" from shell and do "adb.exe shell" again.

5. Pull the files from your device using "adb.exe pull" command:
adb.exe pull /sdcard c:\temp
replace /sdcard with your sdcard directory on the phone (if different) and c:\temp with other folder on your PC, if you wish.


That's it! After files are copied, reboot to stock ROM and reformat the card. You can now copy all data back to it from your PC!

Now I'm trying to find a way to format the card to FAT32. Seems not so straightforward with 64GB cards!


Sincerely,
satanxda
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26th July 2012, 04:47 PM |#2  
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Man! pity I didn't read this before I formatted my "damaged" card ... good to know there's solution for future

Wysyłane z mojego GT-I9300 za pomocą Tapatalk 2
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26th July 2012, 05:31 PM |#3  
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Yeah this needs to be listed in one of the stickies

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26th July 2012, 06:12 PM |#4  
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I had the same problem. From stock went to CM10, exFat got corrupted and then went back to Stock still external storage card showed as damaged.

I took the SD card out and put in adapter and then connected to PC. Then from command prompt ran chkdsk <Drive_Letter:> /f and it fixed the errors without me copying the files to PC.

Hope this helps.
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26th July 2012, 07:41 PM |#5  
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And to format 64GB sd card from exFAT to FAT32, use guiformat tool or EaseUS partition master. I have formatted my card to FAT32 using EaseUS partition master.

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26th July 2012, 08:08 PM |#6  
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With this problem you can restore data in more easily way.
Insert your SDcard in CardReader, connect to PC, run Command line (cmd) and type:
chkdsk X: /f ,
where X is your card volume name. After operations is complete, you can use you card again and NO data had been lost.

Sorry for my bad english.
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26th July 2012, 08:32 PM |#7  
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Quote:
Originally Posted by mahendra1020

And to format 64GB sd card from exFAT to FAT32, use guiformat tool or EaseUS partition master. I have formatted my card to FAT32 using EaseUS partition master.

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Tried it before posting this howto, but EaseUS didn't see the card at all. Windows disk manager in the meantime reported incorrect size (27 GB for a 64 GB card) and when formatted with guiformat I got a 27 GB partition. Could be a problem with card reader - will try another one as soon as I get my hands on one ;]

mahendra1020, magicm3n: in my case using chkdsk was not possible, since Windows showed the SD card as a disk with not formatted RAW partition (suggested to format it). To run chkdsk, partition type must be recognized.

And by the way, thanks everyone for comments and suggestions!


Sincerely,
satanxda
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26th July 2012, 08:36 PM |#8  
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Quote:
Originally Posted by satanxda

Tried it before posting this howto, but EaseUS didn't see the card at all. Windows disk manager in the meantime reported incorrect size (27 GB for a 64 GB card) and when formatted with guiformat I got a 27 GB partition. Could be a problem with card reader - will try another one as soon as I get my hands on one ;]

mahendra1020, magicm3n: in my case using chkdsk was not possible, since Windows showed the SD card as a disk with not formatted RAW partition (suggested to format it). To run chkdsk, partition type must be recognized.

And by the way, thanks everyone for comments and suggestions!


Sincerely,
satanxda

Yeah even in my case windows showed sd card as not formatted but chkdsk still works.

Try /f instead of /r as arguments for chkdsk.

Are u formatting as fat or fat32? For me both the tool worked.

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27th July 2012, 02:14 PM |#9  
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Quote:
Originally Posted by mahendra1020

Yeah even in my case windows showed sd card as not formatted but chkdsk still works.

Try /f instead of /r as arguments for chkdsk.

Are u formatting as fat or fat32? For me both the tool worked.

Sent from my GT-I9300 using xda app-developers app

Probably you are right. Checkdisk button was disabled for me when right-clicking->Properties on the drive, but anyway Windows was reporting wrong size of the card, so I didn't want to risk forcing repairing and didn't invest too much time to that. But as I said, maybe it's the problem of my quite old SD card reader

By the way, successfully formatted from exFAT to FAT32 by using this Android tweak to mount the SD card as USB Mass Storage device on PC (so basically turning the phone itself into a card reader) and formatting in Windows with guiformat:
http://forum.xda-developers.com/show....php?t=1711009
http://www.ridgecrop.demon.co.uk/guiformat.htm



Sincerely,
satanxda
2nd August 2012, 07:34 PM |#10  
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And did you get CM10 to read all of the 64 gigabytes?
For me CM cannot read the SD card over 32 gb.
11th August 2012, 10:02 AM |#11  
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Formatted my 64gb SDCard using EASEUS Partition Master to FAT32.
CM9 recognizes all the 59GB+, reads and writes on the card just fine. Didn't install CM10 yet, so don't know if that will work...
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