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Disk Defragmentation in Windows: What You Need to Know

Published/Updated on Thursday, March 20, 2025

M3 Software author Wilsey Young

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Wilsey Young

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Summary: This post revolves around disk defragmentation on Windows OS and shows how to perform Windows disk defragmentation. The post also involves matters needing attention when it comes to disk defragmentation. -From m3datarecovery.com

disk defragmentation

Some Windows computer users can sometimes sense the apparent slowdown of system performance when HDD (Hard Disk Drive) becomes highly fragmented, such as slower read/write speed, slower system startup, higher CPU or memory usage, etc.

Fortunately, you can count on the disk defragmentation in Windows OS that can help restore the overall performance and efficiency of the system.

Reddit discussion on Windows disk defragmentation

There are heated discussions about Windows disk defragmentation in the post on Reddit. How do geeks and netizens define disk defragmentation on Windows? Do we have to defragment the SSD? What are the differences between an HDD and SSD when it comes to disk defragmentation? Check the following Reddit post for more details.

Disk Defragmenter: Everyone did it but no one knew what it did
by u/o-rka in nostalgia

Disk defragmentation: what does disk defragmentation do in Windows?

Disk defragmentation (AKA defrag, defragmenting) refers to the process of reorganizing the fragmented files on the HDD (Hard Disk Drive), making the files stored in the HDD blocks more contiguous,

In other words, the non-contiguous blocks once allocated to one specific file become adjacent or much closer to each other after disk defragmentation, so the HDD does not have to move its read/write head back and forth to retrieve all the pieces of the fragmented file.
HDD read write head

As a result, since the time to access a target file is reduced, the overall performance of the HDD and system can be improved, at the same time, the life span of the HDD can be extended because of the reduced wear and tear caused by physical movement.

What does disk fragmentation mean? Why do fragmented files appear? Does an SSD need disk defragmentation? Check this post for more details: Should You Defrag SSD? Here's the Best Answer You Want!

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Disk defragmentation: perform disk defragmentation in Windows 10/11

Windows operating system has a built-in disk defragmentation tool that can help you optimize the HDD if needed. Here's how to perform disk defragmentation in Windows 10/11 OS:

  1. Press the Windows+S keys or tap on the search box at the left bottom to open the Windows search box.
  2. Type defragment and optimize drives in the search box and click the result to open.
    search for defragment and optimize drives
  3. Check how strongly the HDD is fragmented.
  4. Click the Analyze button to see if this HDD needs to be optimized.
  5. Click the Optimize button to start the disk defragmentation.
    analyze and optimize fragmented HDD in Windows

You can also perform disk defragmentation through Command Prompt on Windows 10/11:

  1. Press the Windows+S keys to open the Windows search box, 
  2. Type cmd, and select Run as administrator.
    cmd run as administrator
  3. Input defrag X: /O /U /V, replace X with the target drive letter, and hit the Enter key on your keyboard. For example:
    defrag HDD in CMD

 Note: /O stands for optimization, /U shows the progress of the operation, and /V provides a detailed report of defragmentation progress.

Disk defragmentation: matters needing attention

Though disk defragmentation speeds up data access of HDD and overall system performance, it brings downsides if not applied properly. Here are some matters we should pay attention to:

Conclusion

Rational and regular disk defragmentation not only maintains HDD performance but also extends HDD lifespan. Determine whether the HDD needs disk defragmentation based on the analysis given by the built-in tool on Windows.

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