How to generate a disc image from my Raspberry PI 4B?

You can get a Raspberry Pi disk image in a few different ways depending on what you mean:

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1. Downloading an official Raspberry Pi OS image

If you simply want the operating system image to write to an SD card:

Option A — Using Raspberry Pi Imager (easiest)

1. Download Raspberry Pi Imager from the Raspberry Pi website (Windows, macOS, Linux).
2. Open it and choose:
   • Operating System → Raspberry Pi OS (or other OS)
   • Storage → your SD card
3. Click Write.

The Imager will download the correct image automatically, so you don’t need to manually fetch anything.

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Option B — Downloading a raw image file

If you want the .img.xz file directly:

1. Go to the OS download section for Raspberry Pi.
2. Choose your preferred Raspberry Pi OS version.
3. Download the compressed image (*.img.xz).
4. Use Raspberry Pi Imager, balenaEtcher, or dd to write the image to the SD card.

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2. Creating your own disk image from an existing Raspberry Pi

If you want to copy the SD card from your working Pi (e.g., for backup):

On Linux or macOS

Insert the SD card and run:

sudo dd if=/dev/sdX of=raspi-backup.img bs=4M status=progress

sync

Replace /dev/sdX with the actual device (not a partition like sdX1).

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On Windows

Use:

• Win32 Disk Imager
  • Choose a filename
  • Select your SD card
  • Click Read (this creates a .img file from the SD card)

Or use HDD Raw Copy Tool for bit-for-bit cloning.

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3. Creating a disk image of your Pi while it is running

If you want to clone the system without removing the SD card:

Use:

sudo rpi-clone /dev/sdX

But this requires a second device (USB stick, SSD, etc.) attached to the Pi.

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Does that mean that copying SD card on Raspberry PI backs up everything and that there is no internal storage on the Raspberry PI apart from the SD card?

Yes — for most models of Raspberry Pi, the SD card is the only persistent storage. So:

✅ Copying the SD card = backing up absolutely everything

A full-card clone contains:

• the operating system
• your settings
• installed software
• logs
• your home directory
• all radio astronomy scripts, data folders, etc.

As long as you clone the entire device (not just partitions), it’s a complete, bootable backup.

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Does a Raspberry Pi have any internal storage?

Raspberry Pi models with NO internal storage

These store everything on the SD card:

• Raspberry Pi 1 (all models)
• Raspberry Pi 2
• Raspberry Pi 3 (all models)
• Raspberry Pi 4
• Raspberry Pi Zero / Zero W / Zero 2 W
• Raspberry Pi 5 (still boots from SD by default unless using NVMe / USB)

These boards have no eMMC and no NAND flash.
The SD card is the storage.

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Raspberry Pi models that do have built-in eMMC

A few do have internal storage:

• Raspberry Pi 400? → No, still uses SD card
• Raspberry Pi Compute Module (CM3, CM4, CM5) → Some versions can include onboard eMMC
• Industrial / compute variants often use eMMC instead of SD.

So unless you’re using a Compute Module with eMMC, you have no internal storage.

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Bottom line

For a normal consumer Pi:

✔ Clone SD card → complete system backup

✔ Nothing else needs backing up

✔ Restoring the clone to another SD card will reproduce the entire system

Perfect — the Raspberry Pi 4B has no internal storage at all. Everything persistent lives on the micro-SD card unless you have attached an SSD/NVMe via USB and explicitly moved the OS there.

So for your Pi 4B:

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✅ Cloning the SD card backs up the entire system

A full card image includes:

• OS
• configs
• SDR software (e.g., GNU Radio, drivers)
• your scripts, data folders, logs
• bootloader configuration
• everything needed to boot another Pi 4B exactly the same way.

If your SD card dies, writing that image to a new SD card brings the system back instantly.

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🎯 Recommended backup method for a Pi 4B

If removing the SD card is easy

Use a Linux/macOS/Windows computer:

On Linux/macOS:

sudo dd if=/dev/sdX of=pi4_backup.img bs=4M status=progress

sync

On Windows:

Use Win32 Disk Imager → click Read to create a .img file.

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If you want to back up without removing the SD card

Use a USB drive plugged into the Pi and run:

sudo apt install rpi-clone

sudo rpi-clone sda

This creates a full bootable duplicate on the USB drive (or a second SD card in a USB reader).

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