Creating a full backup of the operating system is a critical step before making any changes to the software of your smartphone. Many users ignore this step, relying on cloud services that save only contacts and photos, but do not affect system partitions at all. Losing the bootloader or damaging the partition EFS can turn an expensive device into a useless brick, the restoration of which will require deep technical knowledge.
The procedure for creating a system image (often called Nandroid backup) allows you to preserve the state of the phone exactly as it was at the time of copying. This includes not only user data, but also partition structure, kernel settings, and unique hardware identifiers. Unlike a standard reset to factory settings, such a backup makes it possible to roll back the system even after an unsuccessful installation of a custom recovery or obtaining root access.
There are several methods for implementing this task, each of which has its own advantages and limitations depending on the device model and the state of its software. The choice of a specific method directly depends on whether your bootloader is unlocked and whether a third-party recovery mode is installed. We will look at the most effective options, from using advanced tools on a PC to built-in functions of specialized software.
Device preparation and necessary tools
Before you begin manipulating system partitions, you must ensure the stability of the connection and the presence of all required components. Chaotic connection of cables or the use of non-original wires often leads to a breakdown in communication at the most critical moment of data transfer. Make sure that the battery level is at least 60%, as the image creation process can take a significant amount of time depending on the amount of memory.
To work, you will need a computer with a Windows, Linux or macOS operating system installed appropriate USB drivers for your device. Without correct identification of the gadget in the device manager, no software utilities will be able to access the internal storage at a low level. It is also strongly recommended to use the original USB cable included in the kit, since cheap analogues often transfer data, limited only to charging.
⚠️ Attention: Before starting work, be sure to enable USB debugging mode in the developer menu. Without activating the parameter
USB debuggingthe computer will not be able to send the necessary commands to the device via the ADB interface.
Download and install the package Android SDK Platform-Toolsthat contains the utilities adb i fastboot. These tools are the industry standard for interacting with Android devices at a deep level. Place the files in a convenient directory, for example, in the root of drive C, to simplify entering commands in the terminal or command line.
☑️ Ready to create a backup
Method of creating a copy through custom recovery TWRP
The most reliable and convenient way to save a full copy of the system is to use a custom recovery, such as TWRP (Team Win Recovery Project). This tool works independently of the underlying operating system, which allows you to create images even if Android does not boot correctly, but the bootloader itself is working. The TWRP interface is intuitive and allows you to flexibly configure backup settings.
First, you need to boot into recovery mode. This is usually done by a combination of the power and volume keys with the device turned off, although on some models Samsung or Xiaomi the procedure may differ. After entering the menu, select Backup, where you will be asked to select partitions to copy. It is critical to include partitions Boot, System, Data and EFS (or Modem/Persist), as they contain the kernel, OS files, user data and unique network settings, respectively.
- 📂 Boot —contains the system kernel and ramdisk required to run Android.
- 💾 System — stores operating system files and pre-installed applications.
- 🔐 EFS —critical partition with IMEI, MAC addresses and encryption keys (the loss of this partition is irreparable without factory dumps).
- 📱 Data —includes all installed applications, settings and personal files of the user.
In the backup settings menu you can choose the data compression method. Using the format tar without compression will save more space, but the process will be faster, while compression gzip or zips will save space, but will require more processing time by the processor. For modern devices with fast flash memory, the time difference is not so significant, so it is recommended to use compression to save space on the memory card or internal storage.
Where are TWRP backup files stored?
By default, all backups are saved in a folder /sdcard/TWRP/BACKUPS/, inside which a subfolder is created with a unique device identifier (Serial Number). If you are using an external SD card, the path will be similar, but on external media. Do not delete this folder manually through the Android file manager, so as not to disrupt the directory structure necessary for recovery.
Using the SP Flash Tool for devices on MediaTek
Owners of smartphones built on processors MediaTekhave access to a powerful tool SP Flash Tool, which allows you to work with the device’s memory directly, bypassing the operating system. This method is especially useful if the phone is in a bricked state or if you want to create an exact bit-by-bit copy of the entire flash memory before experimenting with firmware. However, this method requires special care and understanding of the memory structure.
To work, you will need a dispersion file (scatter-file), which describes the memory card of your device. Usually it is extracted from the official firmware or generated by special utilities. After loading this file into the SP Flash Tool, go to the Readbacktab. Here you can add new regions for reading by specifying the starting address and section length, which can be found in the scatter file itself or the chip specifications.
| Parameter | Description | Recommended value |
|---|---|---|
| Start Address | Starting address of the section in hex | From a scatter file (for example, 0x00000000) |
| Length | Size of the partition to copy | Full partition size (for example, 0x2000000) |
| File Name | Name of the created file image | partition_name.img |
After setting the parameters, press the button Read Back and connect the switched off phone to the computer by holding down the volume button (usually down or up, depending on the model). The reading process will proceed automatically, and upon completion you will receive binary partition files. These files can later be used to restore the device through the same utility in Download.
⚠️ Attention: Incorrectly specifying memory addresses in the SP Flash Tool may result in overwriting critical areas or making it impossible to read. Always check the addresses with the original scatter file of your specific model, as they are unique for each device.
Backup via ADB and command line
For advanced For users who prefer control over every step of the process, using the interface ADB (Android Debug Bridge)is ideal. This method does not require installing a custom recovery and works on stock devices with an unlocked bootloader or even on some locked models in recovery mode. The command line allows you to unload individual partitions as images .img.
The first step is to reboot the device into fastboot or bootloadermode. This can be done with the command adb reboot bootloader, if the phone is turned on, or with a hardware button combination. After connecting to the PC, check the visibility of the device with the command fastboot devices. If the serial number is displayed, the connection is established correctly.
To create a copy of a specific partition, use the command fastboot flash in the opposite direction, but since standard fastboot does not have a "read" command, we use an alternative approach through adb pull in recovery mode or specialized scripts. However, if you have root access, you can copy partitions directly from the file system /dev/block/.
adb shell su -c"dd if=/dev/block/bootdevice/by-name/boot of=/sdcard/boot.img"
adb pull /sdcard/boot.img
In the example above, the command dd reads data from the block device corresponding to the partition bootand writes it to a file on the internal drive. Then the utility adb pull transfers this file to the computer. Similarly, you can save partitions recovery, system and others, knowing their exact names in the directory by-name.
Use the command `ls -l /dev/block/platform/*/by-name` in the ADB terminal to see a list of all available partitions and their symbolic links. This will help you accurately determine the names of the partitions for your specific device, since they may differ from the standard ones.
Saving data using Titanium Backup and analogues
If your goal is to save not the entire system image, but exclusively user data and application settings, then specialized Android-based software will cope with this more efficiently. The leader in this area for a long time was Titanium Backup, which requires the presence of root access. This application allows you to freeze, delete and create backup copies of both the applications themselves and their data.
Unlike system backups, this method will not save you if the bootloader is “bricked,” but is ideal when changing the firmware to custom, when you need to transfer settings and progress in games to a new system. In the app menu, select the option Batch actions, then Create a backup copy of all user applications and data. The process may take a long time depending on the amount of installed software.
- 🛡️ Encryption — Titanium Backup allows you to encrypt archives with a password to protect confidential information.
- ☁️ Cloud — Set up automatic uploading of created archives to Dropbox or Google Drive for additional security.
- ⚙️ Filters — You can exclude system applications from the backup so as not to inflate the size of the archive with unnecessary data.
Modern alternatives such as Swift Backup or Migrate, offer a more modern interface and support for new versions of Android, where backup mechanisms have been tightened by Google. These applications also require root access to fully function, but can work in a limited mode via ADB for regular users without superuser rights.
Restoring the system from a created copy
The backup itself is useless if you do not know how to restore it correctly. The rollback procedure depends on the method you used to create the copy. If you worked with TWRP, simply boot into recovery, select Restore, specify the desired date and confirm the operation. The system will automatically overwrite the partitions with data from the archive.
When using SP Flash Tool the recovery process occurs in Downloadmode. You will need to load the same image files that you previously considered into the corresponding rows of the table and click the Downloadbutton. The device will be reflashed bit by bit, returning to a state identical to the moment the copy was made. This is a powerful recovery tool, but it requires that the device's bootloader be at least partially functional.
⚠️ Attention: When restoring an EFS or Modem partition, make sure that the copy was made from that device. Flashing IDs from another phone will result in loss of ability to work in cellular networks and may be irreversible.
In case of recovery via ADB and dd, you will need to boot the phone into recovery mode, which supports shell access, and perform a reverse write operation. The command will look similar to the reading process, but with a change in the direction of the data flow: dd if=/sdcard/boot.img of=/dev/block/bootdevice/by-name/boot. A single letter mistake here can fatally damage the file system.
Always check the integrity of your backup files before deleting the originals. A damaged archive may turn out to be useless at a critical moment, when an urgent restoration of the smartphone's functionality is required.
Is it possible to restore a TWRP backup to another phone model?
Absolutely not. System backups created through TWRP contain hardware-specific drivers and kernel settings. Restoring an image from one model to another will result in a driver conflict, a cyclic reboot (bootloop) or a complete failure of the device. The only exception is some user data, but their transfer is not guaranteed due to differences in paths and resolutions.
How much space is required for a full copy of the firmware?
The amount of space required depends on the size of the partition Data i System. For a modern smartphone with 128 GB of memory, half full, a full backup can take from 20 to 60 GB. It is recommended to use an external SD card or a computer with sufficient free space. Data compression can reduce this volume by 30-50%.
What to do if after recovery the network signal is lost?
Most likely, the partition was damaged or incorrectly restored EFS (or Persist/Modem). Try restoring this particular partition from the most recent backup. If there is no backup of this partition, IMEI restoration is only possible through specialized service utilities (for example, Chimera or Z3X) with certificates, which is a complex procedure.
Is it necessary to make a backup before a regular over-the-air (OTA) update?
For a regular OTA update, a full system backup is usually not required, since the process is officially supported by the manufacturer. However, creating a backup copy of important user data (photos, documents) is always a reasonable precaution in case of failure during the installation process or data loss due to a compatibility error.