tetherback

Tools to create TWRP and nandroid-style backups of an Android device via a USB connection, without using the device's internal storage or SD card.

To guarantee against backup corruption during transfer, it generates md5sums of the backup files on the device and then verifies that they match on the host.

WARNING: This is a work in progress. I have personally tested it on the following device/recovery/host combinations…

Other users have reported success—and issues ☺—with other devices, including picassowifi, cancro, Z00T; and other operating systems, various versions of Windows and Mac OS X.

Requirements and installation

tetherback requires Python 3.3+. In addition, it depends on:

• TWRP recovery installed on your rooted Android device
• adb (Android Debug Bridge) command-line tools
• progressbar2 and tabulate packages from PyPI (fetched automatically during pip install; see below)

Install with pip3 to automatically fetch Python dependencies. (Note that on most systems, pip invokes the Python 2.x version, while pip3 invokes the Python 3.x version.)

# Install latest development version
$ pip3 install https://github.com/dlenski/tetherback/archive/HEAD.zip

# Install a tagged release
# (replace "RELEASE" with one of the tag/release version numbers on the "Releases" page)
$ pip3 install https://github.com/dlenski/tetherback/archive/RELEASE.zip

Usage

Boot your device into TWRP recovery and connect it via USB. Ensure that it's visible to adb:

$ adb devices
List of devices attached
0123deadbeaf5f5f	recovery

• Make a TWRP-style backup over ADB. This saves a gzipped image of the boot partition as boot.emmc.win, and saves the contents of the /system and /data partitions as tarballs named system.ext4.win and data.ext4.win:

  $ tetherback
  tetherback v0.8
  Found ADB version 1.0.32
  Using default transfer method: adb exec-out pipe (--exec-out)
  Device reports kernel 3.4.0-bricked-hammerhead-twrp-g7b77eb4
  Device reports TWRP version 3.0.0-0
  Reading partition map for mmcblk0 (29 partitions)...
    partition map: 100%
  Reading partition map for mmcblk0rpmb (0 partitions)...
    partition map: 100%
  Saving backup images in ./twrp-backup-2016-07-03--14-53-29/ ...
  Saving partition boot (mmcblk0p19), 22 MiB uncompressed...
    boot.emmc.win: 100%   4.0 MiB/s  16.3 MiB
  Saving tarball of mmcblk0p25 (mounted at /system), 1024 MiB uncompressed...
    system.ext4.win: 100%   2.5 MiB/s 299.7 MiB
  Saving tarball of mmcblk0p28 (mounted at /data), 13089 MiB uncompressed...
    data.ext4.win: 100%   2.0 MiB/s 804.0 MiB
  

• Make a "nandroid"-style backup over ADB. This saves gzipped images of the partitions labeled boot, system, and userdata (named <label>.img.gz):

  $ tetherback -N
  tetherback v0.8
  Found ADB version 1.0.32
  Using default transfer method: adb exec-out pipe (--exec-out)
  Device reports kernel 3.4.0-bricked-hammerhead-twrp-g7b77eb4
  Device reports TWRP version 3.0.0-0
  Reading partition map for mmcblk0 (29 partitions)...
    partition map: 100% Time: 0:00:03
  Reading partition map for mmcblk0rpmb (0 partitions)...
    partition map: 100%
  Saving backup images in nandroid-backup-2016-07-03--18-15-03/ ...
  Saving partition boot (mmcblk0p19), 22 MiB uncompressed...
    mmcblk0p19: 100%   3.07 MB/s  16.3 MiB
  Saving partition system (mmcblk0p25), 1024 MiB uncompressed...
    mmcblk0p25: 100%   1.76 MB/s  343.7 MiB
  Saving partition userdata (mmcblk0p28), 13089 MiB uncompressed...
    mmcblk0p28: 100%   1.80 MB/s  6.4 GiB
  

Additional options

• Extra partitions can be included with the -X/--extra and --extra-raw options; for example, -X modemst1 -X modemst2 to backup the Nexus 5 EFS partitions.

  • With --extra-raw, the extra partition will always be saved as a raw image, rather than as a tarball, even if it is a mountable filesystem and tetherback is run in TWRP backup mode.

• The partition map and backup plan will be printed with -v/--verbose (or use -0/--dry-run to only print it, and skip the actual backup). For example, the following partition map and backup plan will be shown for a Nexus 5 with the standard partition layout:

  BLOCK DEVICE    PARTITION NAME      SIZE (KiB)  MOUNT POINT    FSTYPE
  --------------  ----------------  ------------  -------------  --------
  mmcblk0p1       modem                    65536
  ...
  mmcblk0p19      boot                     22528
  ...
  mmcblk0p25      system                 1048576  /system        ext4
  ...
  mmcblk0p28      userdata              13404138  /data          ext4
  mmcblk0p29      grow                         5
                  Total:                15388143
  
  PARTITION NAME    FILENAME         FORMAT
  ----------------  ---------------  -------------------------------------------------
  boot              boot.emmc.win    gzipped raw image
  system            system.ext4.win  tar -cz -p
  userdata          data.ext4.win    tar -cz -p --exclude="media*" --exclude="*-cache"
  

• Additional options allow exclusion or inclusion of standard partitions:

  -M, --media           Include /data/media* in TWRP backup (deprecated: default behavior)
  -D, --data-cache      Include /data/*-cache in TWRP backup
  -R, --recovery        Include recovery partition in backup
  -C, --cache           Include /cache partition in backup
  -U, --no-userdata     Omit /data partition from backup (implies --no-media)
  -E, --no-media        Omit /data/media* from TWRP backup
  -S, --no-system       Omit /system partition from backup
  -B, --no-boot         Omit boot partition from backup
  

Motivation

I've been frustrated by the fact that all the Android recovery backup tools save their backups on a filesystem on the device itself.

• TWRP recovery (code) creates a mixture of raw partition images and tarballs, and stores the backups on the device itself.
• Same with CWM recovery , which creates nandroid-style backup images (just raw partition images) and again stores them on the device itself.

This is problematic for several reasons:

1. Most modern Android smartphones don't have a microSD card slot.
2. There may not be enough space on the device's own filesystem to back up its own contents.
3. Getting the large backup files off of the device requires an extra, slow transfer step.

Clearly I'm not the only one with this problem:

• http://android.stackexchange.com/questions/64354/how-to-do-a-full-nandroid-backup-via-pc
• http://android.stackexchange.com/questions/47975/is-there-a-way-to-do-nandroid-backup-directly-to-pc-and-then-restore-it-directly

I found that @inhies had already created a shell script to do a TWRP-style backup over USB (Gist) and decided to try to put together a more polished version of this.

Issues

One of the very annoying issues with adb is that adb shell is not 8-bit-clean: line endings in the input and output get mangled, so it cannot easily be used to pipe binary data to and from the device. The common workaround for this is to use TCP forwarding and netcat (see this answer on StackOverflow), but this is more cumbersome to code, and prone to strange timing issues. There is a better way to make the output pipe 8-bit-clean, by changing the terminal settings (another StackOverflow answer), though apparently it does not work with Windows builds of adb.

By default, tetherback uses TCP forwarding with older versions of adb, and an exec-out binary pipe with newer versions (1.0.32+). If you have problems, please try --base64 for a slow but reliable transfer method, and please report any data corruption issues. If your host OS is Linux, --pipe should be faster and more reliable.

-t, --tcp             ADB TCP forwarding (fast, should work with any host
                      OS, but prone to timing problems)
-x, --exec-out        ADB exec-out binary pipe (should work with any host
                      OS, but only with newer versions of adb and TWRP)
-6, --base64          Base64 pipe (very slow, should work with any host OS)
-P, --pipe            Binary pipe (fast, but probably only works
                      on Linux hosts)

License

GPL v3 or newer