roottools photo for Nandroid backup guideIf you’re in the root world, you’ve probably heard about nandroid backups before, but you may be wondering exactly what they are and what you can do with them. Since we’ve got a new class of root users with the HTC One M8 (and some returning root heads from the EVO line), I thought it might be time to do a quick guide here.

These are not HTC device specific, but as I’m on the EVO and One lines, if you’re on something else your options may be slightly different.

What are nandroid backups?

At the simplest, a nandroid backup is a snapshot of your phone and how it looks now. This means your programs and data and the ROM you’re running are all backed up into one recoverable location.

A bit of warning: there are no nandroid backups that back up your photos, so be aware of that.

A bit more detailed explanation involves understanding that your phone contains various partitions which make up your phone – these include partitions for your ROM, your data, your applications, the system kernel, the radios, where your pictures/music live, etc.

When you create a nandroid backup, the software that’s doing the backup looks at those partitions and creates a big file containing all the files that were on the partition. Most nandroid backups will back up the boot partition where the kernel lives, the system/ROM partition, and the data and user apps partitions.

If you’ve got space savings selected, these files will be compressed after they’re created.

The nandroid backup will then live in a directory on your phone somewhere and can be restored using a recovery.

What is a recovery?

A recovery is a software application that can be run without booting into the phone’s ROM. The name recovery probably comes from that if your device is messed up, you can get to this mode and recover your OS, data, etc.

In most custom recoveries, you can make a nandroid backup of your phone, you can restore a backup so that you’re in the same spot you were before you did something, or you can flash custom mods and ROMs to your phone.

Once you’re done in recovery, you reboot the phone and your ROM loads up.

It should be noted there are application like OBackup and Live Backup that will allow you to make nandroid backups from within your phone; however, as far as I know, there is no application to completely restore a nandroid other than recovery mode.

Nandroids vs HTC Backup, Titanium Backup

If you accidentally delete an application, you can restore it with Titanium Backup, maybe with HTC Backup, and definitely with a nandroid. A nandroid restore wipes out anything you’ve done since the last nandroid backup, so if you’re just attempting to restore one thing, you end up setting yourself back to the last point you were at when you backed up.

If your ROM has crashed and won’t boot however, no software you run from your phone is going to help you as your phone isn’t running. Booting into recovery mode and restoring a nandroid or flashing a new ROM may be your only hope of getting things back in line.

Common nandroid scenarios

Flashing a ROM

  • Create nandroid backup
  • flash new ROM
  • if something doesn’t work properly, restore previous ROM you backed up before flashing the new ROM

Flashing a mod/tweak/kernel

  • Create nandroid backup
  • flash the mod/tweak/kernel
  • if it broke your phone, restore the nandroid, all better.

Accidentally deleted an app/game

  • Use an application like Titanium Backup or Nandroid Browser to restore that app’s apk and data from the backup.

Common recovery nandroid handling

There are two major recoveries out there in the Android world – Team Win’s Recovery Project and ClockworkMod recovery. On the HTC One M8, I’d suggest using a recovery called PhilZ Touch Recovery because it will work with either format, but that’s just personal preference.

In either case, the backup files are stored in a directory corresponding to the format: ClockworkMod or TWRP, and then the device ID, and a date.

You can keep multiple backups, as many as you have space for, and delete old backups without fear.

Getting into recovery mode

This will vary from phone to phone, but let’s say your phone is locked up. On the HTC One M8 you would press power+volume up until the phone goes black, then press volume down and when the screen turns on sixish seconds later it will pop into a mode called bootloader.

You can select recovery from there.

Switching recoveries

Let’s say you want to try out a different recovery, you switch from PhilZ Touch to TWRP, and suddenly realize that all of your backups are gone and now you suddenly need that data with the fierceness of 1000 suns.

Oh, and somehow your ROM has died, a truckload of cows is stuck on a railroad track, and you’re in a pickle.

Although you might have used an automated android app to install your recovery before, you can switch recoveries from the bootloader using a windows/mac application “fastboot,” or you can copy over a recovery switching Aroma installer and flash it from your current recovery.

Basically, as long as you didn’t delete the old recovery backups, you’re safe. Methods of switching recoveries vary, but there’s always a way.

Scenarios in which you could lose data

Keep in mind that your pictures are not backed up as part of a standard nandroid, and neither are any random SD card contents such as an Excel spreadsheet you might have copied from work.

While most root operations such as flashing, wiping caches, formatting /system, etc., do not touch anything outside of their partition, if you formatted your SD card or you installed an RUU that changes partitions, your internal data will probably be wiped.

Usually you have to deliberately choose these data-destructive options, although I won’t rule out that there might be a way to accidentally do them.

Also, wiping the SD card will generally wipe out your backup directories, although if you’ve saved them to an external SD card you might still be good.

Making a nandroid backup without including the data partition could result in you having a running ROM but no applications.

Any questions?

This is not a complete rundown of everything that’s possible, but it should give you a general rundown of what a nandroid backup is capable of. If you’re ever in a jam and you have a nandroid backup, breathe – it will probably be all right.