By Lily / Last update March 16, 2022

Why Need to Copy Operating System to External Hard Drive?

Operating system makes computer run and it stores a lot of important data. Now, information technology is developing at a high speed. Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11 are popular nowadays. However, the operating system may crash or break all of a sudden

Therefore, some users choose to copy operating system to external hard drive to keep the data safe and the data can be restored immediately after the computer is crashed. And you don't need to reinstall Windows if it crashes, saving much time and effort. 

Besides, you can do so before upgrading system. Therefore, you can return to your old OS and get your data back when the new system goes wrong or you don't enjoy the new OS.

Best Software to Clone Windows to External Hard Drive

Since cloning Windows to external hard drive has so many benefits, how do we implement it. You can use excellent system clone software - AOMEI Backupper Professional. It provides you with two working ways, namely clone system or create a system image. In consideration of simple operation steps, here we recommend you to clone system with this software.

And you can enjoy some useful features in the following: 

It offers you System Clone, Disk Clone and Partition Clone to meet your different needs. To clone Windows to external hard drive, you can try the previous two cloning method and choose them depending on the items you want to include and the disk space of target disk.
It allows you to clone OS on the HDD/SSD and MBR/GPT disk, or directly clone entire disk.
It is able to clone hard drive or SSD with diferent interface, such as, SATA, NVMe, PCIe, M.2, etc.
It is also capable of cloning all brands of disk, such as, Samsung, WD, SanDisk, Seagate, etc.

How to Clone Windows 7 to External Hard Drive Step by Step

Before cloning Windows 7 to external hard drive, you need to download AOMEI Backupper Professional and install it on your computer. And it also applies to migrate Windows 11 to SSD  or other systems. For server users, try AOMEI Backupper Server.

Download Free Trial Win 11/10/8.1/8/7/XP
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(PS: The Clone features in free trial can only be demonstrated, please upgrade now before using it. And you can enjoy 10% discount for one computer.)

Step 1. Launch AOMEI Backupper. Select “System Clone” under the “Clone” tab as shown in the following picture. 

Choose System Clone

Step 2. Select the destination partition for cloning the system. Here take “Disk1” as an example, select it and click “Next”.

Choose Destination Partition

After clicking “Next”, it will pop up a window to remind you the destination partition will be overwritten or deleted. If there isn’t any data on it, click “OK” to go on, or you need to click “Cancel” to cancel the operation and backup the important data first.


Step 3. Confirme the source partitions and destination partition, click “Start Clone” to copy Windows 7 to external hard drive. Well, if transferring OS to SSD, checking the “SSD Alignment” option will optimize the SSD performance.

System Clone Preview

You can set up more by pitching on the options in the left bottom.

  • The “Sector by sector clone” will clone all sectors from source partition to destination partition, which can also take more time to finish.
  • If you are cloning disk to larger disk, there will be one more option called "Make full use of disk space". It's to extend system partition size by unallocated space.

After all the operations, wait for a minute and when the process reaches 100%, click “Finish”. You have done the system clone.


Copying an operating system to an external hard drive with AOMEI Backupper will be extremely simple. And it can further improve the disk performance using 4k alignment technology and extend the size of system partition with its Make full use of disk space.

You can also create a system image by using the “Backup” features. The system backup won’t interrupt your work, so you can backup it while working. And then restore system image to new hard drive if your computer is not responding or stop working.

 In addition, it still supports cloning an SSD to a larger SSD in Windows 10, replace laptop HDD with SSD, clone SATA to NVMe, clone hard drive to Samsung SSD, etc. Anyway, it's worth-trying software for data protection.