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This guide is intended to make a full backup of your android phone (the entire memory block with all partitions) or a single partition (including sdcards, etc) directly to your computer, in either
  • Block level (with dd): for single partitions or whole memory block (all partitions in one piece). The backup always has the same size which is the size of the partition.
  • File level (with tar): only for individual partitions. This only includes files and folders, so occupies much less space, depending on how much filled is the partition.
It can be done with the phone powered on or from ClockWorkMod Recovery (from both ADB works, while in Fastboot doesn't so won't apply). Unless specified the commands meant to be used from Windows. For Linux and Unix is similar.

  • Rooted Android Phone
  • Busybox installed on your phone
  • If you are using Linux / OS X you have native tools, for Windows download Cygwin, and install with it netcat, pv and util-linux. Get them from Cygwin's setup.exe
  • ADB installed.
  • Make sure adb.exe is in your windows' path. See here and here, or use Path Manager.
  • Android phone with USB Debugging enabled, and the proper drivers installed on Windows so the phone is recognized. Typing 'adb devices' on a terminal should show your device.

You now have to identify the partition or block device that you want to backup. For a single partition you can use either tar or dd, while for the entire memory block you can only use dd.
For example, on Galaxy Nexus you have the list of partitions here and for Galaxy S2 here.
Usually on android, the entire block containing all partitions is located at /dev/block/mmcblk0 and the data partitions is a subpartition of it. You can push parted with GPT support to your device and see all information on a partition or block.

Whole phone memory -> /dev/block/mmcblk0 (may vary, in some phones this is the sdcard)
Subpartitions -> depends on each device. Usually at /dev/block/platform/dw_mmc/by-name/ there are listed by name linking to the real device.

Back up of the whole memory block (via adb)
Connect the phone in ADB mode and unlock the screen.
Open one Cygwin Terminal and enter (replace mmcblk0 if needed):
adb forward tcp:5555 tcp:5555
adb shell
/system/xbin/busybox nc -l -p 5555 -e /system/xbin/busybox dd if=/dev/block/mmcblk0
You will see the cursor blinking at the left. Now the phone is waiting to send the block over the network.

Open another Cygwin terminal and type:
adb forward tcp:5555 tcp:5555
cd /path/to/store/the/backup
nc 5555 | pv -i 0.5 > mmcblk0.raw
You will see how the image size is growing until it finishes. Now you have the whole phone backed up in raw format. You can see the contents of the GPT partition with gptfdisk tool, available for windows, linux and such. See official website and sourceforge to get it. You can do it the same from ClockWorkMod Recovery but you have to mount first the /system partition since the busybox included with clockworkmod does not come with netcat and you have to use the one from the system partition.
With further linux tools you could edit or extract single partitions from the whole block.

You can use adb via wifi as well with applications like WiFi ADB.

Back up of the whole memory block (via wifi)

Original post: [Q] Nandroid directly to computer w/o sdcard

We need to install a FTP server on the computer or the other device, configure a user with a password if we want to, and set some port. It uses by default 21 but this example uses 40. We must set a home dir for the user with write permissions.

Usually is a good idea to put myfifo in /cache not in /data because we may overwrite sensitive data in case we want to use that raw image for data recovery.

Open one Cygwin terminal
adb shell
mkfifo /cache/myfifo
ftpput -v -u user -p pass -P 40 COMPUTER_IP block.raw /cache/myfifo
Open another Cygwin terminal
adb shell
dd if=/dev/block/mmcblk0p12 of=/cache/myfifo
- Fifos only can be made on linux native filesystems, for example on a FAT partition is not possible.
- Reading from a partition does not modify it.

Now check on Filezilla Server the speed

Back up of the whole memory block (USB tethering, Wifi tethering)
To use tethering you have to disconnect the computer from all networks and connect it only to the phone with the type of connection you want.
Once you connect it, you can view the IP of the computer and the IP of the phone from connection properties. The ip is the computer ip and the gateway is the phone's ip.
  • Wifi Tethering: Computer <---Wifi---> Phone <---3G---> Internet
  • USB Tethering:
    • Computer <---USB---> Phone <---Wifi---> Internet
    • Conputer <---USB---> Phone <---3G---> Internet
This is exactly the same as via wifi, except that the transfer speed is much higher because the computer and the phone are directly connected, instead of using a router as a gateway. In this case, the gateway is the phone. USB tethering has the highest transfer rate.

Back up of a single partition (raw = every bit of the partition)
It is exactly the same as the the previous but replacing mmcblk0 by the corresponding partition. You can use in this particular case several software to read the partition from windows, depending on partition filesystem: DiskInternals Linux Reader, Ext2Read, Ext2 File System Driver for Windows, Ext4Explore, plugin for Total Commander and ImDisk Virtual Disk Driver. You can also use recovery software on individual partitions like Recuva in combination with VHD Tool or command line tools included with operating systems.

Back up of a single partition (tar = only files and folders)
In this case, you need the partition mounted. To see the list of mounted partitions type on Cygwin Terminal
adb shell mount
Now you need to know where is mounted the partition you want to backup, for example the firmware is mounted on /system, which is the ROM.
In this case you will have to open three terminals, because of android limitations:

Open one Cygwin terminal and create a fifo, in /cache, for example, and redirect the tar there
adb forward tcp:5555 tcp:5555
adb shell
/system/xbin/busybox mkfifo /cache/myfifo
/system/xbin/busybox tar -cvf /cache/myfifo /system
We have to do it this way because redirecting the tar to stdout (with - ) is broken on android and will corrupt the tar file.

Open a second Cygwin terminal and type:
adb forward tcp:5555 tcp:5555
adb shell
/system/xbin/busybox nc -l -p 5555 -e /system/xbin/busybox cat /cache/myfifo
Open a third Cygwin terminal and type:
adb forward tcp:5555 tcp:5555
cd /path/to/store/the/backup
nc 5555 | pv -i 0.5 > system.tar
You can browse the tar file with Winrar, Total Commander, PeaZip and almost any compression tool. Note that you shouldn't extract files or edit it since the tar format saves the permission and owner data for each file, that is lost when extracted to FAT / NTFS partitions and you will mess things when restoring.

Originally Posted by mohsyn

On newer android versions (Im on 7.2) data folder has a folder media which is link to sdcard and one ends up backing up entire sd card. I had a 64gb backup which wasn't necessary

In order to avoid skipping the media folder i had to do some trial and error because busybox tar command is not completely the same as GNU tar.

Would appreciate if you can mention it in the mail guide to use the following command to backup /data folder without copying sdcard files

In first terminal
tar cv --exclude data/media/0 -f /cache/myfifo /data

in 3rd terminal
nc 5555 | pv -i 0.5 > data.tar

no change in second terminal


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