EFS! (Backup, loss, restore)?

[funkylogik]

Im seeing a LOT of people lose their IMEI while flashing custom or factory roms.
I have some backups but i have no idea what makes people lose their EFS, what it really is, or how to restore it.
Could anyone do a decent write-up of
1 what is the EFS file for/what does it do?
2 why/how can it be lost?
3 how can it be backed up, how to protect ourselfs
4 how to restore it when you realise you cant make calls etc and your IMEI has turned into 000049.... or whatever..
In the most universal way possible so we can point affected users to your guide?
It seems like an epidemic in the s3 world right now.. dont know about other devices tbh
Cheers :beer:

 

[Rxpert83]

The s3 was the first device I ever had affected by it, but its certainly not alone in the potential for losing it

I'm on the run right now, but might be able to go into a little more detail once I get to work today

 

[funkylogik]

Nice one bro :beer:

 

[Thom]

I moved this suggestion to the suggestion box.

... Thom

 

[jhawkkw]

I agree, it might be a good idea to add an informative FAQ about it and provide a link to it in each devices FAQ and/or ATR sticky.

 

[Xyro]

Im seeing a LOT of people lose their IMEI while flashing custom or factory roms.
I have some backups but i have no idea what makes people lose their EFS, what it really is, or how to restore it.

I wouldn't say I know much about it either, but it's a partition on your device (/efs) where things such as IMEI codes and other important stuff are stored. It can get wiped whilst messing around with root related stuff, and since the data stored in there is unique to your phone, you can't fix it without already having a backup.

 

[PaulS]

I was going to install a custom rom on my GT S5830i but have not got round to it as I'm happy with my rooted Gingerbread 2.3.6 for now but I downloaded all the files I needed and backed up all critical data including the EFS just in case for which I used Galaxy Too Box<free>,

https://play.google.com/store/apps/details?id=com.doky.sgtoolbox&hl=en_GB

and keep regularly updated CWM(Clock Work Mod )backups on my 32 gig SD card and computer.

HTH

 

[funkylogik]

Yeah. Ktool by Hellcat will work on international (not north america) galaxy devices to backup and aparently restore EFS. I think it backs up as an .img file but i also have .tar backups.
These are the type of things i/we need clarification on :thumbup:

 

[Slug]

It was/is quite common on the S2 also, so much so that many third-party kernels now back /efs up during their installation flash. I'm sure Paul Hawker authored a post dealing with the problem.... I'll try to dig it up.

edit: it wasn't him but one of the other 'Musketeers'. Still informative though.
http://androidforums.com/galaxy-s2-...t/431515-warning-back-up-your-efs-folder.html