Should you compress your OS drive to save disk space?

Compressing an operating system disk is a way to save space on a computer’s hard drive. More storage space is available by reducing file sizes. Since the operating system disk is often full of duplicate assets, configuration files, and code, people have theorized that compressing the operating system disk can free up a significant amount of space. With existing transparent compression file systems, users can use their files transparently without manually compressing and decompressing them.

So, should you compress your OS disk? What are the risks and what does transparent compression mean?

What is transparent compression?

A file system is what structures all of your files so that the computer can easily store and retrieve data when needed. Some file systems allow transparent compression, while others do not. For example, Windows uses three common file systems, and only one (NTFS) allows transparent compression.

Having file systems with transparent compression, such as NTFS, allows you to compress the OS disk. Transparent compression is a file system feature that automatically compresses and decompresses files, folders, and disks.

Since the file system or operating system is responsible for compressing and decompressing files. User can access and work with files. Depending on the processing power of your CPU and the load it is currently under, you may or may not experience performance drops.

Since your OS disk contains various application files that you use every day, it is important to have a transparently compressed file system so that machines can read and write files continuously, even when compressed.

What are the advantages of compressing your OS disk?

Compressing your OS disk has become a feature of some operating systems because it provides a number of advantages that may be useful for some machines. This can be a risky process, but depending on your machine and the files on your OS drive, it can be a viable option with some benefits, such as:

  • Increased storage space: OS disk compression results in smaller file sizes, allowing more data to be stored on your hard drive.
  • Performance improvement: Computer performance can be faster with smaller files on the operating system drive because the system can access compressed files faster than uncompressed files—but only when the CPU isn’t running at full capacity.
  • Reduced saving size: Backing up a compressed OS disk results in smaller backup files, which saves time and memory.
  • Reducing network traffic: Compressed files take up less space, which means less data needs to be transferred over the network. This can be useful when working with remote servers or transferring large files over the Internet.

Great! But compressing your OS disk has downsides and even risks.

Possible Disadvantages and Risks of Compressing Your OS Drive

A worried boy with a laptop

Automatic compression and decompression of files and folders by transparent filesystems is a convenient way to save space, but why not use it on the OS drive? Before doing so, there are a number of potential risks and drawbacks associated with OS disk compression. Here are a few:

  • System instability: Compressed OS disks add an extra layer of processing to access and write data. This can cause system instability and crashes.
  • Slow performance: On a compressed OS disk, the CPU has to use some of its resources to compress and decompress files, which adds latency every time it tries to access the files.
  • Data loss: Sometimes there is a compression problem and results in data loss. Although this rarely happens, having your files constantly compressed increases the risk of data corruption.
  • Problem Solving Difficulty: Troubleshooting and diagnosing problems can be difficult if the operating system is compressed because it can hide the underlying problem.
  • Compatibility issues: When moving hard drives to another computer, some systems may not support the file system or transparent compression type used on your OS drive.

The likelihood of these issues occurring depends on your computer’s hardware, the files stored on your primary drive, and whether or not your operating system supports transparent disk compression.

Which operating systems support disk compression?

Not all operating systems support hard disk compression. Let’s talk about which ones do, which ones don’t, and possible solutions.


For Windows 7 and later, Microsoft natively enabled disk compression with the NTFS file system. Therefore, compressing your C:/ drive in Windows is the easiest to achieve as it is natively supported. All you need to do is format your drive to use NTFS, then enable transparent file compression by going to the properties of the C:/ drive and checking the “Compress contents to save disk space” option.


As for PCs using Linux, they can use the Brfts file system for operating system compression. Brfts is supported by several popular Linux distros like Arch Linux, Debian, Fedora, Ubuntu, Manjaro and Red Hat.

Linux servers can use the ZFS file system supported by Fedora, Debian and Cent OS.

If you’ve been using Linux for a while, you should be able to flash your OS drive relatively easily. Although some Linux distributions support NTFS, it can read and write data without being able to change permissions.


Unfortunately, compressing your OS drive for macOS is not as easy as it is for Windows and some Linux distros. Although MacOS supports transparent compression via HFS+, it does not provide users with the tools to do so. So as a solution, you need to install Homebrew and use third party tools like afsctool.

Need to decompress your OS disk?

Generally, it is not recommended to compress your OS disk due to the risk of system instability and slow performance.

However, in some cases, you may need to compress your OS drive to free up space and squeeze more performance out of your computer.

If you’re using an old computer, it should be acceptable to squeeze your OS disk as a last ditch effort to have a usable machine, because you really have no choice.

More modern computers can compress their OS disk if their machine has a fast CPU and a slow hard drive. Having the CPU process files in the background should help alleviate the bottleneck as the CPU is not being used to its full potential due to hard disk bandwidth limitations.

Compacting the OS disk should be a last resort

Although OS disk compression can save you a significant amount of storage space and even improve performance, the risk is not worth it because there are other ways to save storage space.

The obvious solution to your storage problem is to buy a new hard drive. But if you don’t know how to replace a hard drive, there are still many ways to save space and improve performance. For example, you can remove unnecessary programs, clean temporary files, defragment your hard drive, use disk cleaning programs like CCleaner, or simply compress files and folders instead of the OS disk itself.

Even if your operating system supports OS drive compression natively, keep in mind that this is really meant to be used as a last resort and should not be your first choice to save disk space.

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