understanding CWM, backups, EFS partition, etc.

[billp000]

Can you help me to understand something?

I have unlocked the bootloader on my LG Optimus G device. I've done a backup in recovery mode of both the EFS partition (a ZIP file) and, supposedly, the ROM.

1. Now, does this mean I can do anything I want with my phone, assured that I will always be able to restore based on the two backups I did?
2. In what situation do I restore EFS partition? In what situation do I restore the ROM?
3. What good is the EFS partition if I backed up the ROM? Why would I ever need to use that?
4. If my phone won't boot up or encounters another security error, can I simply restore the ROM that I have backed up? Why do so many forums mention using KDZ and other tools when a phone is "bricked?"
5. If I brick my phone, will I definitely be able to enter into Recovery, or can that Recovery function also be messed up? Is there a situation in which I will not be able to enter into Recovery? (Note: I had to unlock the bootloader on my LG phone which enabled the Recovery feature. I'm assuming that there's something that can also destroy this Recovery feature.)

Thanks for your explanation. I've read up on some of these things, but I still don't feel that they are presented in layman's terms.

 

[ryanrazer]

Okay, EFS partition is special partition dedicated for your phones info like radio signal info, imei and such. If you encounter problems with connections this might be the cause. But it's a rather delicate thing so for now just keep it backed up and don't touch it. It should cause problems... Normally rooting, flashing ROMs, unlocking and locking bootloader, flashing ZIP. files, kernels and custom recoveries shouldn't harm EFS partition as it is well secured and independent. If you encounter before mentioned connection problems it is probably due to APN settings. EFS is the last thing you should mess with....

If you are stuck to bootloop (system doesn't boot) you should first boot to custom recovery and erase cache partition, dalvik partition and if that doesn't help just do a full wipe (cache, dalvik and factory reset) and reflash the ROM. Ofc assuming you have ROM saved on your phone in a from of ZIP. file. When flashing custom ROMs i always keep multiple versions in case one is damaged, so i can try another one. But you can mount storage via recovery so this isn't fatal, as you can transfer new ROM on your phone via USB cable when mounted.

If you manage to prevent your phone to boot into recovery you must be a real pro in phone bricking... In that case you should boot into bootloader and re-flash custom recovery. Then you'll be good to go.

I hope that helps,
Cheers!

 

[Rukbat]

1) There are two "Android" partitions, the ROM and recovery. If you backed up the ROM, but mess up the recovery, you can't restore it from the ROM backup. Since recovery is another partition with a whole operating system on it, yes, you can brick the recovery. (But you can usually flash a custom recovery, like CWM or TWRP. Usually. You can mess the phone up so badly that you can't even do that.)

2) There are 2 conditions referred to as bricking, hard brick and soft brick. A soft brick is a messed up ROM (like a boot loop or the phone boots to the carrier's logo, then freezes). You can usually recover from that by reflashing the ROM. Each manufacturer has its own programs to use to do that.

With a hard brick, the phone acts the same whether it has a battery or not - it sits there like a brick. Nothing you do makes any difference - it doesn't flash lights, it doesn't start to boot, it doesn't buzz or vibrate, it just sits there. Assuming the hardware isn't fried, about the only way to fix a hard brick (except with some Samsung devices) is by using a JTAG box. Since a good one isn't cheap, and it takes experience to use, the best bet is to find a JTAG service - either searching with a search engine or on eBay - and pay them to restore the phone.

If you have to ask about the EFS partition, back it up, make a copy of the backup on your computer and another copy on a cloud account and forget about it. If someone you're paying to fix the phone asks if you backed up the EFS partition you can give him the backup. But DON'T restore it yourself. Just restoring the EFS backup can brick the phone.

Bottom line - until you can answer most of these questions yourself, don't play "unsupported" games with the phone. Don't flash ROMs, don't run one click rooting programs, etc. Just read and learn. Eventually you'll know enough to know what you can do and what you shouldn't do. Most people can drive cars, but most shouldn't try making a 180 degree turn in zero distance in the middle of a busy intersection, although once you learn how to do it, making the car spin 180 degrees isn't much more than very difficult. Once you learn how a phone works and how to use the various tools to undo the mess you make, fixing the mess isn't difficult at all, it's just time consuming. (And a little nail-biting, as you wait to see if the phone is going to come back after you did what you did - the first boot takes a lot longer than normal.

 

[ellisroy]

Great answers.

Verizon gs4 rooted and still learning

 

[Rukbat]

Great answers.

Thank you.

still learning

That's the great part - many people don't want to - they want to know all of it right now. Keep learning. When we stop learning it's time to start nailing the coffin shut. (As Dwayne Pride, Scott Bakula's character on NCIS NOLA, says - go and learn something.)

 

[YIN YAN]

Great quote, great content... Thx.. coffin almost closed!

 

[YIN YAN]

What a great summary... A book condense in a post... Amazing!! doing a refresher but IMEI unlock is a provider connection arena; if you know someone inside your ok; else we use online unlocking methods. Completely away from how we teach them in the scene about software and hardware hacks but I guess we need to keep it like this in this new age; To guaranteed oUr spot and earnings in this new age. Tip: IMEI efs manipulation might be the way via EFS partition; risky but the only option at this time without and inside conection; is going to be havock once all the phones start coming in but this is what is going on in Caribbean and other parts of USA. RUKBAT ur the man; nice post!