[SOLVED][Guide] How to backup EFS + Modemfs folders

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YMatrix

YMatrix

Senior Member
Feb 3, 2013
811
292
Samsung Galaxy S20 FE
Samsung Galaxy Watch
Hello!

So I recently stumbled upon some information that while flashing all kinds of Roms, you might lose your IMEI, thus being left over with a nice paper weight.
To my understanding this information is stored in the EFS folder (though according to this thread it is actually stored in modemfs).
I googled around and saw many options: PC software, terminal commands, apps etc.
Since each phone utilizes this option in different ways, which would be a good way to backup these folders in case of emergency on the S Advance?

Thanks!

SOLUTION:

These are the commands from the ADB shell, but can also be used within the terminal.

Backup Process:
Code: 
adb shell
su
dd if=/dev/block/mmcblk0p7 of=/sdcard/efs_backup.img
dd if=/dev/block/mmcblk0p2 of=/sdcard/modemfs_backup.img 
exit
exit
adb pull /sdcard/efs_backup.img efs_backup.img
adb pull /sdcard/modemfs_backup.img modemfs_backup.img

Restore Backup Process:
Code: 
adb push efs_backup.img /sdcard/efs_backup.img
adb push modemfs_backup.img /sdcard/modemfs_backup.img
adb shell
su
dd if=/sdcard/efs_backup.img of=/dev/block/mmcblk0p7 
dd if=/sdcard/modemfs_backup.img of=/dev/block/mmcblk0p2 
exit
exit

Thanks to @mr.harsh and @KINGbabasula for help and KINGbabasula for making the script!
Please note that the restore commands haven't been tested out, but theoretically its supposed to work.
If someone has made a backup and wiped his EFS folder, he wont mind testing it out :D
 

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BOOTMGR

BOOTMGR

Senior Member
Aug 3, 2010
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3,395
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YMatrix said:
Hello!

So I recently stumbled upon some information that while flashing all kinds of Roms, you might lose your IMEI, thus being left over with a nice paper weight.
To my understanding this information is stored in the EFS folder (though according to this thread it is actually stored in modemfs).
I googled around and saw many options: PC software, terminal commands, apps etc.
Since each phone utilizes this option in different ways, which would be a good way to backup these folders in case of emergency on the S Advance?

Thanks!
Click to expand...
Click to collapse
in the terminal type:
Code: 
su
cp /dev/block/mmcblk0p7 /sdcard/efs_backup
cp /dev/block/mmcblk0p2 /sdcard/modemfs_backup

check that efs_backup is 10MB and modemfs_backup is 16MB.And this is for JB.I don't know about GB but most probably they'll be same...
 
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YMatrix

YMatrix

Senior Member
Feb 3, 2013
811
292
Samsung Galaxy S20 FE
Samsung Galaxy Watch
Thank you for your quick reply.
I tested it out and got the sizes you said.
The restore process, if ever needed, is the same cp command only changing the source and destination?
Whats the difference between the CP command and the DD command?
Any way to do this from recovery or ADB?

Sent from my GT-I9070 using Tapatalk 4 Beta
 
Last edited:
KINGbabasula

KINGbabasula

Inactive Recognized Developer
Jan 28, 2013
2,301
5,167
Treviso
YMatrix said:
Thank you for your quick reply.
I tested it out and got the sizes you said.
The restore process, if ever needed, is the same cp command only changing the source and destination?
Whats the difference between the CP command and the DD command?
Any way to do this from recovery or ADB?

Sent from my GT-I9070 using Tapatalk 4 Beta
Click to expand...
Click to collapse

Via adb:
Code: 
adb shell
$ su
# cp /dev/block/mmcblk0p7 /sdcard/efs_backup
# cp /dev/block/mmcblk0p2 /sdcard/modemfs_backup
# exit
$ exit
adb pull /sdcard/efs_backup %cd%\efs_backup
adb pull /sdcard/modemfs_backup %cd%\modemfs_backup
 
Last edited:
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YMatrix

YMatrix

Senior Member
Feb 3, 2013
811
292
Samsung Galaxy S20 FE
Samsung Galaxy Watch
KINGbabasula said:
cp=copy dd=copy, convert, format. See my reply. I updated
Click to expand...
Click to collapse

Still don't get the difference DD / CP :p
As for the commands you posted, I was asking for the restore process, so I am guessing it will look like this:
Code: 
adb shell
$ su
# cp /sdcard/efs_backup /dev/block/mmcblk0p7 
# cp /sdcard/modemfs_backup /dev/block/mmcblk0p2 
# exit
$ exit
Is there a "push" command also (to be used like the pull command)?
 
KINGbabasula

KINGbabasula

Inactive Recognized Developer
Jan 28, 2013
2,301
5,167
Treviso
YMatrix said:
Still don't get the difference DD / CP :p
As for the commands you posted, I was asking for the restore process, so I am guessing it will look like this:
Code: 
adb shell
$ su
# cp /sdcard/efs_backup /dev/block/mmcblk0p7 
# cp /sdcard/modemfs_backup /dev/block/mmcblk0p2 
# exit
$ exit
Is there a "push" command also (to be used like the pull command)?
Click to expand...
Click to collapse

I'm not sure but i think that you need to use dd to restore because you are going to flash 2 partition like flashing kernel.
You can do this (i repeat Im not sure)
Code: 
adb push efs_backup /sdcard/efs_backup
adb push modemfs_backup /sdcard/modemfs_backup
adb shell
$ su
# dd if=/sdcard/efs_backup of=/dev/block/mmcblk0p7 
# dd if=/sdcard/modemfs_backup of=/dev/block/mmcblk0p2 
# exit
$ exit

Pay attention cause if you dd to a wrong partition you may brick
 
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YMatrix

YMatrix

Senior Member
Feb 3, 2013
811
292
Samsung Galaxy S20 FE
Samsung Galaxy Watch
KINGbabasula said:
I'm not sure but i think that you need to use dd to restore because you are going to flash 2 partition like flashing kernel.

Pay attention cause if you dd to a wrong partition you may brick
Click to expand...
Click to collapse

Hmmm, so this is a pickle.
Wrong partition is always a problem, but since I also checked a thread by @frapeti, I am assuming the partition numbers are correct, though I don't know about the commands. Since we saved using CP shouldn't we also restore using CP? Otherwise I would say save using DD and then restore using DD.
 
KINGbabasula

KINGbabasula

Inactive Recognized Developer
Jan 28, 2013
2,301
5,167
Treviso
YMatrix said:
Hmmm, so this is a pickle.
Wrong partition is always a problem, but since I also checked a thread by @frapeti, I am assuming the partition numbers are correct, though I don't know about the commands. Since we saved using CP shouldn't we also restore using CP? Otherwise I would say save using DD and then restore using DD.
Click to expand...
Click to collapse

No because cp copy the content of the partition. dd format the partition then copy in the partition
 
YMatrix

YMatrix

Senior Member
Feb 3, 2013
811
292
Samsung Galaxy S20 FE
Samsung Galaxy Watch
KINGbabasula said:
No because cp copy the content of the partition. dd format the partition then copy in the partition
Click to expand...
Click to collapse

Oh, alright, so to sum up so people can use this for future reference:

Backup Process:
Code: 
adb shell
$ su
# cp /sdcard/efs_backup /dev/block/mmcblk0p7 
# cp /sdcard/modemfs_backup /dev/block/mmcblk0p2 
# exit
$ exit

Restore Backup Process:
Code: 
adb push efs_backup /sdcard/efs_backup
adb push modemfs_backup /sdcard/modemfs_backup
adb shell
$ su
# dd if=/sdcard/efs_backup of=/dev/block/mmcblk0p7 
# dd if=/sdcard/modemfs_backup of=/dev/block/mmcblk0p2 
# exit
$ exit
 
KINGbabasula

KINGbabasula

Inactive Recognized Developer
Jan 28, 2013
2,301
5,167
Treviso
YMatrix said:
Oh, alright, so to sum up so people can use this for future reference:

Backup Process:
Code: 
adb shell
$ su
# cp /sdcard/efs_backup /dev/block/mmcblk0p7 
# cp /sdcard/modemfs_backup /dev/block/mmcblk0p2 
# exit
$ exit

Restore Backup Process:
Code: 
adb push efs_backup /sdcard/efs_backup
adb push modemfs_backup /sdcard/modemfs_backup
adb shell
$ su
# dd if=/sdcard/efs_backup of=/dev/block/mmcblk0p7 
# dd if=/sdcard/modemfs_backup of=/dev/block/mmcblk0p2 
# exit
$ exit
Click to expand...
Click to collapse

Now i make a script to automate it
 
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arffrhn

arffrhn

Senior Member
Mar 12, 2013
1,583
763
Kuala Lumpur
Hi, I just wanna ask. Can I just copy the efs and modemfs folders to ext sd, then to restore I just copy and replace both files to its actual location using any root explorer (ie: es file manager)? Just asking as I read this guide on backing imei part.
 
frapeti

frapeti

Inactive Recognized Developer
Mar 23, 2012
1,048
4,224
Cordoba, Argentina
www.groupon.com.ar
YMatrix said:
Oh, alright, so to sum up so people can use this for future reference:

Backup Process:
Code: 
adb shell
$ su
# cp /sdcard/efs_backup /dev/block/mmcblk0p7 
# cp /sdcard/ /dev/block/mmcblk0p2 
# exit

[/QUOTE]

Thats wrong, to backup using cp use something like cp [original efs] [sdcard/backup folder]

I guess it's better to use dd command for this purpose:

dd if=/dev/block/mmcblk0p7 of=/sdcard/efs_backup.img

dd if=/dev/block/mmcblk0p2 of=/sdcard/modemfs_backup.img

To restore just switch if with of (input file / output file)

Sent from my GT-I9070 using xda app-developers app
Click to expand...
Click to collapse
 
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  • 7
    YMatrix
    YMatrix
    Hello!

    So I recently stumbled upon some information that while flashing all kinds of Roms, you might lose your IMEI, thus being left over with a nice paper weight.
    To my understanding this information is stored in the EFS folder (though according to this thread it is actually stored in modemfs).
    I googled around and saw many options: PC software, terminal commands, apps etc.
    Since each phone utilizes this option in different ways, which would be a good way to backup these folders in case of emergency on the S Advance?

    Thanks!

    SOLUTION:

    These are the commands from the ADB shell, but can also be used within the terminal.

    Backup Process:
    Code: 
    adb shell
su
dd if=/dev/block/mmcblk0p7 of=/sdcard/efs_backup.img
dd if=/dev/block/mmcblk0p2 of=/sdcard/modemfs_backup.img 
exit
exit
adb pull /sdcard/efs_backup.img efs_backup.img
adb pull /sdcard/modemfs_backup.img modemfs_backup.img

    Restore Backup Process:
    Code: 
    adb push efs_backup.img /sdcard/efs_backup.img
adb push modemfs_backup.img /sdcard/modemfs_backup.img
adb shell
su
dd if=/sdcard/efs_backup.img of=/dev/block/mmcblk0p7 
dd if=/sdcard/modemfs_backup.img of=/dev/block/mmcblk0p2 
exit
exit

    Thanks to @mr.harsh and @KINGbabasula for help and KINGbabasula for making the script!
    Please note that the restore commands haven't been tested out, but theoretically its supposed to work.
    If someone has made a backup and wiped his EFS folder, he wont mind testing it out :D
    View
    4
    frapeti
    frapeti
    YMatrix said:
    Oh, alright, so to sum up so people can use this for future reference:

    Backup Process:
    Code: 
    adb shell
$ su
# cp /sdcard/efs_backup /dev/block/mmcblk0p7 
# cp /sdcard/ /dev/block/mmcblk0p2 
# exit

[/QUOTE]

Thats wrong, to backup using cp use something like cp [original efs] [sdcard/backup folder]

I guess it's better to use dd command for this purpose:

dd if=/dev/block/mmcblk0p7 of=/sdcard/efs_backup.img

dd if=/dev/block/mmcblk0p2 of=/sdcard/modemfs_backup.img

To restore just switch if with of (input file / output file)

Sent from my GT-I9070 using xda app-developers app
    Click to expand...
    Click to collapse
    View
    3
    BOOTMGR
    BOOTMGR
    YMatrix said:
    Hello!

    So I recently stumbled upon some information that while flashing all kinds of Roms, you might lose your IMEI, thus being left over with a nice paper weight.
    To my understanding this information is stored in the EFS folder (though according to this thread it is actually stored in modemfs).
    I googled around and saw many options: PC software, terminal commands, apps etc.
    Since each phone utilizes this option in different ways, which would be a good way to backup these folders in case of emergency on the S Advance?

    Thanks!
    Click to expand...
    Click to collapse
    in the terminal type:
    Code: 
    su
cp /dev/block/mmcblk0p7 /sdcard/efs_backup
cp /dev/block/mmcblk0p2 /sdcard/modemfs_backup

    check that efs_backup is 10MB and modemfs_backup is 16MB.And this is for JB.I don't know about GB but most probably they'll be same...
    View
    2
    YMatrix
    YMatrix
    arffrhn said:
    Yeah that's why I asked. Wondering if I do anything wrong and it won't work when restoring.
    Click to expand...
    Click to collapse

    Copying the folders in theory should also work, its just safer to back them up using the DD command since you get the original structure, permissions, dates etc. of the partitions.
    Thus when restoring its as if you never tampered with them, while the "copy folder" method doesn't give you the original data structure.
    Again, it shouldn't make a difference (in theory), but we always like to be closest to the original ;)
    View
    2
    YMatrix
    YMatrix
    fredrickaein said:
    Hi,

    I was trying to take backup of these folders, but before that, i thought of having a look at the actual folder in the root for their sizes.

    efs = 87 files, 12 folder. total six=ze is 4.84Kb
    modemfs = This folder is empty.

    Now please tell is if these are normal sizes. If it is normal then how come their backup is 10 & 16 Mb respectively.
    Regards,
    Fred
    Click to expand...
    Click to collapse

    I am surprised that your modemfs folder is empty :eek:
    As for the folder size vs. backup size, this is because that these folders are actually partitions on the phone. when backing up using DD / CP commands you are backing up the whole partition (even the "empty" bits of data), which is why you get the according sizes (these are the partition's sizes).
    View

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