[Q] What does a nandroid backup contain?

kirkers said:

When I perform a backup from recovery (or via a front-end such as ROM Manager), what exactly is saved?

Is it like a clone of a hard drive in the PC world?

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That's a pretty close analogy. Only difference is I don't think it captures partitions...but I'm not sure about that. (It's not clear to me, for instance, if you did a nandroid of a phone with the EXT4 mod implemented and tried to install it on a phone without the EXT4 mod, exactly how that would play out.)

As an example, though, I took a nandroid of my stock phone immediately after I rooted it and got S-off. I then played around with various CM7, CM9, and JB ROMs for a weekend, but reloaded the stock nandroid Sunday night before going back to work on Monday. (I need a reliable phone for work.)

My phone was restored to exactly the way it was when I took the nandroid snapshot. I had to re-download a handful of app updates and email that had arrived since the time I took the nandroid to "catch up" to the present time, but that's all.

kirkers said:

When I perform a backup from recovery (or via a front-end such as ROM Manager), what exactly is saved?

Is it like a clone of a hard drive in the PC world?

Does it contain only data, and not the actual ROM?

How should I go about using such a backup when doing a restore? Should a ROM be installed first, followed by the restore? If so, must the ROM match the backup exactly -- that is, must it be the ROM under which the backup was performed in the first place?

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It is everything on your phone at the current time when you made a backup. Including your rom, apps, files, boot animation and e.t.c.

Sent from my EVO using Tapatalk 2

kirkers said:

Thanks for the clarifications and the personal experience story. It helps calm my nerves. :fingers-crossed: Now it is clear that the nandroid is a full snapshot, close to being a clone image.

Can anyone address MysticCobra's point about the EXT4 partition?

As a rule, I have followed ROM Manager app's recommendation to partition the sdcard to allow apps to be stored on it. This is what the EXT4 partition is designed to do, as far as I understand such things.

If I format the sdcard with EXT4 (which in my experience wipes out all data on the card), and then restore a nandroid that came from an older EXT4-formatted sdcard of the same size or smaller than the new sdcard, would the nandroid restoration go smoothly?

What would happen if the new sdcard did NOT have an EXT4 partition?

Thanks in advance for further advice.

:good: Cheers!

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Nandroid backup/restores don't touch the sdcard. They backup to the sdcard but the nandroid only handles /system, /data, /data/data, /cache, boot, and recovery.

The ext4 partition is not the same as the ext4 mod that MysticCobra mentioned. The mod converts /data, and /cache to ext4 and changes the ramdisk to mount them as ext4. The no data limit one also disables the mounting /data/data so the phone will share the apps and app data with a 750MB. Your app data is intact with the no data limit mod but a backup is still advised. No wipe updates don't touch the filesystem in /data or /cache but the mod may need to be flashed again for the ROM to boot correctly as the ramdisk is overridden on all updates. Technically with the normal data one you are good on later cm7 and ICS/JB ROMs as it's already ext4.

If you want to undo the mod the best thing is to wipe /data and /cache and reflash the ROM.

For further reading check the first link in the link below:

http://xdaforums.com/showthread.php?t=1623038