What is a Nandroid backup and how do you do it on Android?

If you've ever tinkered with your mobile phone installing ROMs, doing root or by changing the recovery, you've surely heard of the Nandroid backupsThey are that lifeline that can save you from a big scare when something goes wrong and the phone stops working, gets stuck in a bootloop, or starts malfunctioning for no apparent reason.

In this article you will see in detail What exactly is a Nandroid, what is it used for, and how do you create one step by step?This guide also includes a technical overview of how Android works internally and why this type of backup is so powerful. The goal is that, by the time you finish reading, you'll not only be able to follow a tutorial, but also understand what's happening under the hood of your device.

What is a Nandroid backup and why is it so important?

A Nandroid backup is a Complete backup of the internal state of your Android device at a specific moment. It doesn't just save your photos or apps: it captures system partitions, user data, Boot (boot) and, depending on the recovery, even the recovery partition or the EFS/modem partition in some models.

Unlike backups you make with Android apps, a Nandroid backup is done from a recovery environment (custom recovery such as TWRP or similar) And, in many advanced workflows, it is complemented by tools such as use ADBThis environment starts up separately from the main system and can read and clone entire blocks of memory as if they were disk images, much like what is done on PCs with programs such as Clonezilla or Ghost.

The big advantage is that, when you restore a Nandroid, the phone goes back to the exact state it was in at the time of the copySame ROM, same apps, same kernel, same settings, same bugs if there were any… everything. That's why, before flashing a new ROM, manually updating, or trying risky mods, it's almost essential to have a backup like this saved.

This form of copying relies on how Android is built internally: a system based on the Linux kernelwith several well-defined partitions and software layers that communicate through APIs and drivers. Precisely because the structure is modular, the recovery system can copy specific partitions without needing to boot the entire system.

How is Android organized internally and what does it have to do with Nandroid?

Android is a mobile operating system that relies on the Linux kernel for managing memory, processes, security and hardwareOn top of that kernel are built different layers: native C/C++ libraries, the runtime environment (Dalvik/ART), the application framework and, above all, the apps you use every day.

On a physical level, all of this is divided into several partitions of storageThe usual ones are: boot (kernel and ramdisk), system (system files and vendor layer), vendor (drivers and specific hardware components), data (apps and user data), cache, recovery and, on some devices, special partitions such as EFS (network identifiers) or modem.

The recovery partition, where the Nandroid tools run, has direct access to these partitions. From there you can create compressed images of memory blocksThis way, not only the visible content is copied, but the entire structure of each partition. That's why the restoration is so accurate and the device boots up as if nothing had happened.

In addition, Android uses a Hardware Abstraction Layer (HAL) It acts as an intermediary between the apps and the actual hardware (camera, GPS, sensors, etc.). All the hardware is exposed to the system through drivers in the Linux kernel and native libraries, while the apps communicate using a Java/Kotlin framework. The Nandroid copy doesn't delve so much at the API level, but rather at the block level, so it includes everything that makes up that runtime environment.

Regarding code execution, up to Android 4.4 most applications ran in the virtual machine Dalvikwith just-in-time (JIT) compilation. Since Android 5.0, ART (Android Runtime) has been used, which compiles apps to native code at the time of installation. In a Nandroid backup, both Dalvik and ART are reflected in the system and data images, so you don't have to worry about which runtime engine is being used: the backup includes everything.

Advantages and limitations of Nandroid backups

The first major advantage of a Nandroid is that it acts as Total protection against logical brickingIf you install a ROM that doesn't work well, if a modified kernel causes bootloops, or if a system mod breaks something critical, instead of struggling with partial flashes, you can simply restore your backup and return to exactly where you started.

Another important advantage is that the process is quite independent of the ROM or customization layer It doesn't matter what you're using: it could be a stock Samsung ROM with One UI, a Xiaomi MIUI, a pure AOSP ROM, or an alternative like LineageOS or GrapheneOS. Recovery works at the partition level, not the interface, so the general procedure for creating and restoring a Nandroid backup changes very little between devices.

However, it's important to understand that this type of backup isn't magic. A Nandroid backup is very closely tied to the... hardware and partition structure of your phone. You can't back up on one model and restore it on a completely different one, nor is it a good idea to restore an old Nandroid over a partition structure that has changed due to a major Android update without knowing exactly what you're doing.

It also doesn't replace more granular backups. Although a Nandroid backup includes your data and applications, it's often practical to combine it with other backup methods, such as syncing with [unclear - likely a specific backup method]. Google Drive, Google Photos, or specific copies of important foldersas the save APK of an installed app.

Finally, size must be taken into account. When copying entire partitions, a Nandroid file can take up a lot of space. several gigabytes depending on the content of your device. It is recommended to have sufficient free space in the internal memory or, ideally, on a fast microSD card to store them without problems.

Android as an operating system: context to better understand Nandroid

Android is today the dominant mobile operating system worldwide, with a share that is clearly above iOS In most countries, especially in markets like India, Brazil, and Spain, it is based on the Android Open Source Project (AOSP), primarily licensed under Apache, to which each manufacturer then adds its own layer.

The system originated at Android Inc., a company founded in 2003 that Google acquired in 2005. The platform was announced in 2007 alongside the Open Handset Alliance, a consortium of manufacturers and operators (Samsung, LG, Motorola, Qualcomm, among many others) that aimed to promote open standards for mobile devices. The first terminal The first commercial Android device was the HTC Dream, launched in 2008.

Since then, Android has been receiving constant updates Up to version 9, Android devices were identified by dessert names in alphabetical order (Cupcake, Donut, Eclair, Froyo, Gingerbread, Honeycomb, Ice Cream Sandwich, Jelly Bean, KitKat, Lollipop, Marshmallow, Nougat, Oreo, and Pie). Starting with Android 10, a primarily numerical naming system was adopted, although dessert names are still used internally.

With each version, improvements have been introduced in security, permissions management, graphics performance, multimedia support, and developer toolsFurthermore, interface details have been refined first with Material Design, and later with Material You (Material 3), which dynamically adapts the system's color palette to your wallpaper.

Fragmentation, however, remains one of its weaknesses: not all devices receive updates at the same time, and many models are stuck on older versions. This same fragmentation is yet another reason to value the Nandroid backupsbecause they allow you to maintain a stable "return point" even if the manufacturer doesn't take great care with updates.

Key Android components related to backups

At the top layer are the user applicationsEmail, SMS, browser, maps, contacts, etc. Many come pre-installed by Google (Gmail, Maps, YouTube, Drive) or by the manufacturer, but all rely on the same set of APIs from the application framework.

Below we have the application frameworkThis API exposes services such as activities, background services, content providers, the notification system, window management, the package manager, and permission management itself. Any developer creating an Android app essentially works against these APIs.

Below are the native libraries In C/C++, they are responsible for critical tasks such as the web rendering engine (originally WebKit), the graphics engine, OpenGL ES, the SQLite database, multimedia libraries, SSL, and the C standard library (Bionic). All of this runs on the Linux kernel, which is the one that actually interacts with the hardware.

The runtime, whether Dalvik or ART, acts as the layer that executes the code of the apps and manages the memory of each process. Each app runs in its own virtual machine or isolated process, which improves security and stability: if one application crashes, it shouldn't drag down the rest of the system.

Finally, at the base, the Linux kernel 2.6 and later It handles hardware drivers, the network stack, process scheduling, and memory management. Android also relies on this level to implement features such as power saving, multi-touch support, Bluetooth, GPS, sensors, and a long list of other capabilities that apps then use in an abstract way.

Current Android features and functions

Visually, Android is ready for different screen sizes and resolutionsFrom compact mobile phones to tablets, televisions, and car systems, the system supports 2D and 3D graphics acceleration, and the interface is drawn using libraries optimized to take advantage of the GPU.

For internal storage, Android primarily uses SQLite as a lightweight database engineIn addition to the classic file system in flash memory, each app has its own. private space within /data, which other applications cannot access directly without special permissions or root.

In terms of connectivity, the platform supports a wide range of mobile and network technologiesGSM/EDGE, CDMA, UMTS, HSPA, LTE, and 5G in the latest versions, plus Wi-Fi, Bluetooth, NFC, and other options. For messaging, in addition to SMS and MMS, Android integrates push notification services via Firebase Cloud Messaging (FCM).

El Web navigator By default, historically based on WebKit and the V8 JavaScript engine, it has been converging with Google Chromealthough the user can always install Other browsers such as Firefox, Opera, or Chromium variantsAt the multimedia level, it supports common formats such as WebM, H.264/H.265, MP3AAC, OGG, WAV, JPEG, PNG, GIF and many more depending on the version and hardware.

Android also provides support for streaming of contentsThis has been achieved through RTP/RTSP protocols, progressive streaming in HTML5, and provider-specific solutions. This has enabled the expansion of video and music platforms on mobile devices and Android TV.

Android app development and system interaction

To create Android applications, the following is mainly used: Android Studio as the official development environmentThis IDE includes the Android SDK, emulators, debugging tools, performance analyzers, and graphical interface wizards. Eclipse with the ADT plugin was previously used, but today Android Studio is the standard.

The most common languages ​​for programming apps are Java and KotlinHowever, native components can also be written in C or C++ using the NDK (Native Development Kit). This is useful for games and performance-intensive applications where existing libraries need to be reused.

Google offers a very complete documentation The developer site includes code samples, design guides, interaction best practices, and Material Design guidelines. Furthermore, the development community is enormous, with forums, open-source repositories, and third-party libraries for almost any need.

All these aspects of the development ecosystem are equally reflected in a Nandroid backup: by including the data and system partitions, the backup contains both the downloaded apps and their internal state, configurations and databases, for example for save game progressWhen you restore, it's as if you never uninstalled or modified anything.

Security, privacy, and the role of Nandroid backups

Over the years, Android has been the subject of analysis by security companies and government agencies. Comparative studies have indicated that, although iOS may accumulate a greater number of reported vulnerabilitiesAndroid tends to receive more real attacks, partly because it is the dominant platform and because it allows the installation of apps from outside of official stores.

Google has reacted by tightening its security mechanisms: App verification on Google Play, stricter sandboxing, granular permissions, and default data encryption and tools like Google Play Protect. Even so, the user still plays a key role, especially when unlocking the bootloader, rooting the device, or installing custom recoveries to perform a Nandroid flash.

In the area of ​​privacy, there have been cases where certain location or synchronization options have raised concerns. Features such as the collection of geolocation data or integration with map services They have sometimes been used by intelligence agencies to intercept information, according to leaked documents.

For those who make deep modifications to the system, a Nandroid is not only a safeguard against failures, but also a way to try more privacy-friendly settingsYou can install security-focused ROMs, disable or remove unwanted services, and if you're not happy with the result, easily revert to the previous state by restoring the backup.

However, you must be careful when storing and managing these backups. A Nandroid backup contains all your personal data, identifiers, accounts, and messagesSo storing it in an insecure location or sharing it without encryption would be a serious security mistake.

Android on the market and long-term support

In terms of adoption, Android is used in mobile phones, tablets, smart TVs, watches, cars and even household appliancesIts open-source nature and flexibility have allowed manufacturers worldwide to integrate it into hardware of very different ranges and prices.

Recent statistics show that newer versions of the system, such as Android 13 and 14They are gaining ground, but they still coexist with older versions like Android 10, 11, or even 9 on many devices. This influences how developers need to design their apps and underscores the importance of maintaining reliable backups.

The update support cycle varies greatly depending on the manufacturer: Google devices (Pixel) typically have several years of major updates and security patcheswhile other lower-end models may lose support relatively soon.

In that context, advanced users turn to custom ROMs to extend the lifespan of your devicesThis is where Nandroid backups become especially useful: when changing ROMs, kernels, or recoveries, keeping a complete copy of the previous system allows you to revert if something isn't working properly or if the new version is unusable.

In short, Android has become a huge and very diverse ecosystemIn this environment, where all kinds of devices, varied customization layers, and inconsistent update policies coexist, mastering tools like Nandroid backups gives you much more flexibility to navigate this ever-changing landscape with confidence.

Now that you know in detail how Android works internally, how its partitions are organized, what role recovery plays, and what information is saved in a Nandroid backup, it's much easier to see why this complete backup is the best lifeline when you decide to experiment with ROMs, rooting, kernels, or any deep modification: understanding the system and having a full image of your device's status It's the combination that allows you to explore without fear and, if something goes wrong, recover your phone exactly as it was with a couple of taps from recovery mode.