Root Backing up EFS partition

[DMedina559]

I've seen a lot of post about not being able to backup the EFS partition. So I've got somewhat of a solution. Just requires root and a terminal emulator (adb works too)
In terminal just do:

and it'll make a backup img of that partition. I'm not sure about restoring it with Android booted butI think there's adb access in recovery. There is a terminal emulator in twrp.

 

[codyedmonson]

EDIT: [DELETED]

 

[Masterchief87]

dfuse06 consulted with another developer and what he told me is that the partitions you actually need to backup are modemst1 and modemst2. Of course you could also make an efs.img just in case. The best way to restore is with a recovery flashable zip or an Odin flashable tar. Restoring while booted in android can cause problems and possibly make the situation worse.

 

[Masterchief87]

I went ahead and made a backup of efs.img modemst1.img and modemst2.img using terminal emulator. Here's a screenshot.
Edit: its kinda funny that the 3 img files that I got added up to 20MB but when I zipped them up the zip was only 3MB

 

[johnnyl1111]

the image is of the whole partition. even blank space. kind of like an iso.

 

[Masterchief87]

I've been told that for some reason, the images you pull with this command will almost certainly be corrupted and can cause major problems if you restore them. If you really feel the need to backup efs it is best to find another method.