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[IMPORTANT] How To Do EFS Backup And Restore For GT-I8552

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mrgwin
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Quote:
Originally Posted by kinchit1495 View Post
I think it ws wrong it should be sdcard0

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Nope. mine works fine, the output should be efs.img
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I think bs stands for block size. But can anyone explain what it does?

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Quote:
Originally Posted by coolkoushik07 View Post
Ur given command is wrong. There is no sdcard directory, it would be sdcard0 or extSdCard. By the way can u tell me what is the work of bs command. Somewhere i saw people use bs=4096 while using dd command. Can u please explain it?

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---------- Post added at 08:42 PM ---------- Previous post was at 07:53 PM ----------

Edit : my bad. Ur code is working too. I did a mistake by /storage/sdcard/ so it gave error. So ignore that part. But if u can please explain bs parameter.

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The /sdcard/ *should* be universal on many samsung devices (at least I know it IS like that on the Galaxy Ace and on the Galaxy Win, i8550L that I own).

Regarding the bs operand of the dd command, in this case you don't need it, as you're acting directly over the EFS partition. In the use of this command the bs operand is used for when you're working with a whole disk.

Technical stuff below:

 

For example, if you don't have the precise /dev/block/mmcblk0pXXX of a partition (taking in consideration that /dev/block/mmcblk0 is the disk you want to read from), you can use dd in this way:

Code:
dd if=/dev/block/mmcblk0 bs=4096 of=/sdcard/kernel.img
In the example, we're backing up the Kernel part of the phone (note that this is not real information, just an example, so don't blame me if you try to dump that command back in the phone assuming things you don't know xD), as you may (or may not) know, a disk is comprised of many blocks, you can google about that later :P it's quite late and don't wanna go on too deep so i'll try to be brief; if your disk is 512 mb in size, probably the first 32MB would be for boot, kernel, recovery, modem and NVRAM (not to be confused with modem), these 32 MB might be distributed this way:

1-1024MB Bootloader
1024-6144 Kernel+Recovery
6144-18432 Modem
18432-32768 NVRAM
and so on


Long story short, don't mess with DD
 
Arinio
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Default Backing Up EFS Partition

Dear Jaspreet,

Myself and CoolKoushik07 tested this procedure long before. However this is not working solution. This is due to the natture of the EFS filesystem.

Please go through my Post # 39,40,41,42,43,44.

http://forum.xda-developers.com/show...2541198&page=5

Please correct me if I am wrong.

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Jaspreet_Singh
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Quote:
Originally Posted by Arinio View Post
Dear Jaspreet,

Myself and CoolKoushik07 tested this procedure long before. However this is not working solution. This is due to the natture of the EFS filesystem.

Please go through my Post # 39,40,41,42,43,44.

http://forum.xda-developers.com/show...2541198&page=5

Please correct me if I am wrong.

Regards
Check ur command "dd if=/dev/block/mmcblk0p3 of=/storage/extSdCard/efs.img"

and mine "dd if=/dev/block/mmcblk0p16 of=/sdcard/efs.img"

Two mistakes ? first is our mounting point for efs is mmcblk0p16 and there is no storage "of=/storage/extSdCard/efs.img" it shud be either to sdcard directly or of=/extSdCard/efs.img
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coolkoushik07
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Quote:
Originally Posted by Jaspreet_Singh View Post
Check ur command "dd if=/dev/block/mmcblk0p3 of=/storage/extSdCard/efs.img"

and mine "dd if=/dev/block/mmcblk0p16 of=/sdcard/efs.img"

Two mistakes ? first is our mounting point for efs is mmcblk0p16 and there is no storage "of=/storage/extSdCard/efs.img" it shud be either to sdcard directly or of=/extSdCard/efs.img
Just a lil correction.. /storage/extSdCard/ is not wrong directory..

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Arinio
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Default Backing Up EFS Partition

Dear Jaspreet,

Please check my Post #43.

Regards

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