Boot Ubuntu ISO from Your Hard Drive: A Step-by-Step Guide

Booting an operating system from a USB drive or DVD is a common practice. However, there are scenarios where you might not have a USB drive readily available or your computer’s optical drive is malfunctioning. In such cases, booting directly from the hard drive using an ISO image becomes an invaluable solution. This method is particularly useful for testing new operating systems, performing system recovery, or installing a different OS alongside your existing one. This comprehensive guide will walk you through the process of booting an Ubuntu ISO image directly from your hard drive, providing detailed steps and explanations to ensure a smooth experience.

Why Boot from Hard Drive?

Before diving into the technical details, let’s outline the advantages of booting an ISO image from your hard drive:

Convenience: No need for a USB drive or DVD. The ISO image resides directly on your hard drive, making it easily accessible.
Speed: Booting from a hard drive is generally faster than booting from a USB drive or DVD.
Flexibility: You can store multiple ISO images on your hard drive and choose which one to boot from.
Durability: Hard drives are generally more durable than USB drives or DVDs, reducing the risk of data loss.
Testing and Recovery: Ideal for testing new operating systems without permanently installing them or for performing system recovery when other boot methods fail.

Prerequisites

Before you begin, ensure you have the following:

An Ubuntu ISO Image: Download the desired Ubuntu ISO image from the official Ubuntu website (ubuntu.com). Make sure to download the correct version (Desktop or Server) and architecture (32-bit or 64-bit) for your system.
A Partition on Your Hard Drive: You’ll need a partition on your hard drive to store the ISO image. This partition should be formatted with a file system that your bootloader can recognize (e.g., ext4, NTFS, FAT32). A separate partition is highly recommended to avoid potential conflicts with your existing operating system.
A Bootloader: You’ll need a bootloader (e.g., GRUB, Windows Boot Manager) to recognize and boot the ISO image. GRUB is the most common bootloader on Linux systems, while Windows Boot Manager is used on Windows systems. This guide will primarily focus on using GRUB, as it offers greater flexibility and is commonly used in dual-boot environments.
Root or Administrator Privileges: You’ll need root or administrator privileges to modify bootloader configurations and copy the ISO image to the designated partition.
Basic Command-Line Knowledge: Familiarity with basic command-line commands will be helpful, especially when working with GRUB.

Step-by-Step Guide: Booting Ubuntu ISO from Hard Drive

This guide will cover two primary scenarios: booting from a hard drive with an existing Linux installation (using GRUB) and booting from a hard drive with an existing Windows installation (using GRUB4DOS).

Scenario 1: Booting from a Hard Drive with an Existing Linux Installation (Using GRUB)

This is the most common scenario for users who already have a Linux distribution installed on their system. We will be modifying the GRUB configuration to add an entry for the Ubuntu ISO image.

Step 1: Create a Dedicated Partition (Recommended)

While not strictly required, creating a dedicated partition for the ISO image is highly recommended. This helps keep your system organized and prevents accidental deletion of the ISO image.

You can use a partitioning tool like gparted to create a new partition. gparted is a graphical partition editor that is available on most Linux distributions. Here’s how to use gparted:

Install GParted: If GParted is not already installed, you can install it using your distribution’s package manager. For example, on Ubuntu/Debian, you can use the following command:
```
sudo apt update
sudo apt install gparted
```
Launch GParted: Open GParted from your applications menu or by typing sudo gparted in a terminal.
Select the Hard Drive: Choose the hard drive where you want to create the partition from the dropdown menu in the top-right corner.
Unmount the Partition: If the partition you want to shrink is mounted, you’ll need to unmount it. Right-click on the partition and select “Unmount”.
Resize an Existing Partition (if necessary): If you don’t have enough unallocated space, you’ll need to resize an existing partition to create space for the new partition. Right-click on the partition you want to resize and select “Resize/Move”. Drag the arrows to adjust the size of the partition. Be careful not to resize the system partition too much, as this could cause problems.
Create a New Partition: Right-click on the unallocated space and select “New”.
Partition Settings: Configure the following settings:
- New size (MiB): Specify the size of the new partition. Ensure it’s large enough to accommodate the Ubuntu ISO image (usually around 4-5 GB). Adding extra space for potential future ISOs is a good idea.
- File system: Choose a file system that GRUB can recognize. ext4, FAT32, and NTFS are all good choices. ext4 is generally recommended for Linux systems.
- Label: Give the partition a label (e.g., “ISO”). This will make it easier to identify the partition later.
Add the Partition: Click “Add” to add the partition to the pending operations.
Apply Changes: Click the green checkmark icon to apply the changes. GParted will then create the new partition. This process may take some time, depending on the size of the partition and the speed of your hard drive.

Step 2: Copy the Ubuntu ISO Image to the Partition

Once you have created the partition, you need to copy the Ubuntu ISO image to it.

Mount the Partition: Mount the partition you created. You can do this by clicking on the partition in your file manager or by using the mount command in the terminal. To mount using the command line, you first need to identify the partition’s device name. You can use the lsblk command to list all block devices and their partitions.
```
lsblk
```
The output will show a list of devices, such as /dev/sda, /dev/sdb, etc. Each device may have multiple partitions, such as /dev/sda1, /dev/sda2, etc. Identify the partition you created (e.g., /dev/sdb1 based on the label you gave it).
Create a Mount Point (if necessary): If you don’t have a dedicated mount point for the partition, you’ll need to create one. A mount point is a directory where the contents of the partition will be accessible.
```
sudo mkdir /mnt/iso
```
Mount the Partition: Use the mount command to mount the partition to the mount point.
```
sudo mount /dev/sdb1 /mnt/iso
```
Replace /dev/sdb1 with the actual device name of your partition.
Copy the ISO Image: Copy the Ubuntu ISO image to the mounted partition using the cp command.
```
sudo cp /path/to/ubuntu.iso /mnt/iso
```
Replace /path/to/ubuntu.iso with the actual path to your Ubuntu ISO image.
Unmount the Partition (optional): Once the ISO image is copied, you can unmount the partition.
```
sudo umount /mnt/iso
```
Unmounting is optional, but it’s a good practice to prevent accidental modification of the ISO image.

Step 3: Modify the GRUB Configuration

Now, you need to modify the GRUB configuration to add an entry for the Ubuntu ISO image. This will allow you to select the ISO image from the GRUB menu during boot.

Identify the GRUB Configuration File: The GRUB configuration file is typically located at /boot/grub/grub.cfg or /boot/grub2/grub.cfg. However, you should not directly edit this file, as it’s automatically generated. Instead, you should modify the /etc/grub.d/40_custom file.
Open the 40_custom File: Open the /etc/grub.d/40_custom file in a text editor with root privileges.
```
sudo nano /etc/grub.d/40_custom
```
or
```
sudo vi /etc/grub.d/40_custom
```
Choose your preferred text editor.
Add the GRUB Entry: Add the following lines to the 40_custom file. You will need to adjust the set iso_path, set loop_file, and search lines to match your system’s configuration.
```
menuentry "Boot Ubuntu ISO" {
 set iso_path="/iso/ubuntu.iso"  # Path to the ISO image on the partition
 set loop_file="(hdX,Y)"		  # Replace X with the hard drive number and Y with the partition number

 loopback loop $loop_file$iso_path
 linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$loop_file$iso_path splash
 initrd (loop)/casper/initrd.lz
}
```
- set iso_path="/iso/ubuntu.iso": This line specifies the path to the Ubuntu ISO image on the partition. Adjust this path to match the actual location of the ISO image. For example, if you copied the ISO image to the root of the /dev/sdb1 partition, the path would be /ubuntu.iso. If you created a directory called “isos” on the partition and copied the ISO image there, the path would be /isos/ubuntu.iso.
- set loop_file="(hdX,Y)": This line specifies the hard drive and partition where the ISO image is located. You need to replace X with the hard drive number and Y with the partition number. Hard drive numbering starts from 0, so hd0 refers to the first hard drive, hd1 refers to the second hard drive, and so on. Partition numbering starts from 1. To determine the correct values for X and Y, you can use the lsblk command or the fdisk -l command.
```
sudo fdisk -l
```
  This command will list all the partitions on your system. Identify the partition where you copied the ISO image and note its device name (e.g., /dev/sdb1). The hard drive number is the number after hd, and the partition number is the number after the last letter of the device name. For example, if the device name is /dev/sdb1, then X would be 1 and Y would be 1. Therefore, the set loop_file line would be set loop_file="(hd1,1)".
- loopback loop $loop_file$iso_path: This line creates a loopback device for the ISO image.
- linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$loop_file$iso_path splash: This line specifies the kernel to boot from the ISO image. The boot=casper option tells the kernel to boot into a live environment. The iso-scan/filename=$loop_file$iso_path option tells the kernel where to find the ISO image. The splash option enables the graphical splash screen.
- initrd (loop)/casper/initrd.lz: This line specifies the initial RAM disk to use.
Save the File: Save the 40_custom file and exit the text editor.
Make the Script Executable: Make the 40_custom script executable.
```
sudo chmod +x /etc/grub.d/40_custom
```
Update GRUB: Update the GRUB configuration to include the new entry.
```
sudo update-grub
```
This command will regenerate the grub.cfg file and include the entry you added in the 40_custom file.

Step 4: Reboot Your System

Reboot your system and select the “Boot Ubuntu ISO” entry from the GRUB menu. Your system should now boot into the Ubuntu live environment.

Scenario 2: Booting from a Hard Drive with an Existing Windows Installation (Using GRUB4DOS)

If you have Windows installed on your system, you can use GRUB4DOS to boot the Ubuntu ISO image. GRUB4DOS is a bootloader that can be installed on Windows systems and used to boot various operating systems, including Linux distributions.

Step 1: Download and Install GRUB4DOS

Download the latest version of GRUB4DOS from a reputable source (e.g., SourceForge). Extract the downloaded archive to a folder on your hard drive.

Download GRUB4DOS: Search for “GRUB4DOS download” on your preferred search engine and download the latest version from a trusted source.
Extract the Archive: Extract the downloaded archive to a folder on your hard drive (e.g., C:\grub4dos).
Copy grldr and menu.lst: Copy the grldr and menu.lst files from the extracted folder to the root directory of your C: drive. These files are essential for GRUB4DOS to function correctly.

Step 2: Configure Windows Boot Manager

You need to configure the Windows Boot Manager to load GRUB4DOS during boot.

Open Command Prompt as Administrator: Open a command prompt with administrator privileges. You can do this by right-clicking on the Start button and selecting “Command Prompt (Admin)” or “Windows PowerShell (Admin)”.
Use bcdedit to Create a Boot Entry: Use the bcdedit command to create a new boot entry for GRUB4DOS.
```
bcdedit /create /d "GRUB4DOS" /application bootsector
```
This command will create a new boot entry with the description “GRUB4DOS”. The output of this command will include a GUID (Globally Unique Identifier) for the new boot entry. You will need this GUID in the next step.
Set the Device and Path: Use the bcdedit command to set the device and path for the new boot entry.
```
bcdedit /set {GUID} device partition=C:
 bcdedit /set {GUID} path \grldr
```
Replace {GUID} with the GUID you obtained in the previous step. This command sets the device to the C: drive and the path to the grldr file.
Set the Default Boot Entry (Optional): If you want GRUB4DOS to be the default boot entry, you can use the following command:
```
bcdedit /default {GUID}
```
Replace {GUID} with the GUID you obtained in the previous step.
Set the Timeout (Optional): You can also set a timeout for the boot menu using the following command:
```
bcdedit /timeout 10
```
This command sets the timeout to 10 seconds.

Step 3: Copy the Ubuntu ISO Image to the Partition

Copy the Ubuntu ISO image to a partition on your hard drive, just as you did in Scenario 1. It’s recommended to create a dedicated partition for the ISO image to keep your system organized.

Step 4: Modify the `menu.lst` File

The menu.lst file is the configuration file for GRUB4DOS. You need to modify this file to add an entry for the Ubuntu ISO image.

Open the menu.lst File: Open the C:\menu.lst file in a text editor with administrator privileges.
Add the GRUB Entry: Add the following lines to the menu.lst file. You will need to adjust the find --set-root and iso_path lines to match your system’s configuration.
```
title Boot Ubuntu ISO
 find --set-root /ubuntu.iso
 iso_path=/ubuntu.iso
 loopback loop $iso_path
 linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$iso_path splash
 initrd (loop)/casper/initrd.lz
```
- title Boot Ubuntu ISO: This line specifies the title of the boot entry.
- find --set-root /ubuntu.iso: This line searches for the ISO image on the hard drive and sets the root device to the partition where the ISO image is located. Replace /ubuntu.iso with the actual path to your ISO image. This path is relative to the root of the drive. For example, if your ISO image is located at `D:\isos\ubuntu.iso`, then the line should be `find –set-root /isos/ubuntu.iso`. GRUB4DOS will search all partitions for a file matching this path and set the root device accordingly.
- iso_path=/ubuntu.iso: This line assigns the path to the ISO image to the variable `iso_path`. Again, replace `/ubuntu.iso` with the actual path to your ISO image.
- loopback loop $iso_path: This line creates a loopback device for the ISO image.
- linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$iso_path splash: This line specifies the kernel to boot from the ISO image. The boot=casper option tells the kernel to boot into a live environment. The iso-scan/filename=$iso_path option tells the kernel where to find the ISO image. The splash option enables the graphical splash screen.
- initrd (loop)/casper/initrd.lz: This line specifies the initial RAM disk to use.
Save the File: Save the menu.lst file and exit the text editor.

Step 5: Reboot Your System

Reboot your system. You should now see the GRUB4DOS menu. Select the “Boot Ubuntu ISO” entry from the menu. Your system should now boot into the Ubuntu live environment.

Troubleshooting

If you encounter any problems during the boot process, here are some troubleshooting tips:

Verify the ISO Image: Make sure the Ubuntu ISO image is not corrupted. You can verify the ISO image by comparing its checksum with the checksum provided on the Ubuntu website.
Check the GRUB Configuration: Double-check the GRUB configuration file (/etc/grub.d/40_custom or C:\menu.lst) for any errors. Make sure the paths to the ISO image and the kernel are correct.
Use the Correct Hard Drive and Partition Numbers: Ensure you have used the correct hard drive and partition numbers in the GRUB configuration. You can use the lsblk or fdisk -l command to identify the correct values.
Disable Secure Boot: If you are using a UEFI system, you may need to disable Secure Boot in the BIOS settings. Secure Boot can prevent the system from booting from unsigned bootloaders like GRUB4DOS.
Try a Different Bootloader: If you are having trouble with GRUB or GRUB4DOS, you can try using a different bootloader, such as Syslinux or rEFInd.
Check the BIOS Boot Order: Make sure your hard drive is set as the primary boot device in the BIOS settings.
Consult the Ubuntu Documentation: The Ubuntu documentation provides detailed information about booting from an ISO image.
Search Online Forums: Search online forums for solutions to common boot problems.

Conclusion

Booting an Ubuntu ISO image from your hard drive is a convenient and efficient way to test new operating systems, perform system recovery, or install a different OS alongside your existing one. By following the steps outlined in this guide, you can successfully boot Ubuntu from your hard drive and enjoy the benefits of this versatile boot method. Remember to double-check your GRUB configuration and troubleshoot any problems that may arise. With a little patience and attention to detail, you’ll be able to boot Ubuntu from your hard drive with ease.

Additional Tips

Persistent Storage: When booting from an ISO, changes are not typically saved. To create persistent storage, you can add the persistent option to the linux line in your GRUB configuration. This will create a persistent overlay file where changes are saved. Note that this may require additional configuration steps and is not always reliable.
Multiple ISOs: You can store multiple ISO images on the same partition and create separate GRUB entries for each one. This allows you to easily switch between different operating systems or versions.
Automated GRUB Configuration: There are tools available that can automate the process of creating GRUB entries for ISO images. These tools can simplify the process and reduce the risk of errors.

How to Do

Get clear, simple answers to all your questions. We resolve your doubts.

Boot Ubuntu ISO from Your Hard Drive: A Step-by-Step Guide

Why Boot from Hard Drive?

Prerequisites

Step-by-Step Guide: Booting Ubuntu ISO from Hard Drive

Scenario 1: Booting from a Hard Drive with an Existing Linux Installation (Using GRUB)

Step 1: Create a Dedicated Partition (Recommended)

Step 2: Copy the Ubuntu ISO Image to the Partition

Step 3: Modify the GRUB Configuration

Step 4: Reboot Your System

Scenario 2: Booting from a Hard Drive with an Existing Windows Installation (Using GRUB4DOS)

Step 1: Download and Install GRUB4DOS

Step 2: Configure Windows Boot Manager

Step 3: Copy the Ubuntu ISO Image to the Partition

Step 4: Modify the `menu.lst` File

Step 5: Reboot Your System

Troubleshooting

Conclusion

Additional Tips

Why Boot from Hard Drive?

Prerequisites

Step-by-Step Guide: Booting Ubuntu ISO from Hard Drive

Scenario 1: Booting from a Hard Drive with an Existing Linux Installation (Using GRUB)

Step 1: Create a Dedicated Partition (Recommended)

Step 2: Copy the Ubuntu ISO Image to the Partition

Step 3: Modify the GRUB Configuration

Step 4: Reboot Your System

Scenario 2: Booting from a Hard Drive with an Existing Windows Installation (Using GRUB4DOS)

Step 1: Download and Install GRUB4DOS

Step 2: Configure Windows Boot Manager

Step 3: Copy the Ubuntu ISO Image to the Partition

Step 4: Modify the menu.lst File

Step 5: Reboot Your System

Troubleshooting

Conclusion

Additional Tips

Step 4: Modify the `menu.lst` File