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All the files on my desktop and every file I downloaded from the Internet have suddenly been compressed in Windows 10 (as indicated by two blue arrows on the top right of the icons). I have never set such a setting in Windows. Is this a virus or something else?

My hard drive is 128GB SSD and with 5GB free space.

So why is this happening? Is there an option to turn this behaviour off?

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    Possible duplicate of Two blue arrows at top right of icons
    – Run5k
    Commented Dec 7, 2018 at 14:46
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    Please take a look at this answer. It is probably being caused by Windows Updates.
    – Run5k
    Commented Dec 7, 2018 at 14:47
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    That is understandably frustrating. On the other hand, you probably wouldn't want to miss installing critical operating system security patches, and maintaining an OS partition with only 4% free disk space is destined to be problematic.
    – Run5k
    Commented Dec 7, 2018 at 20:47
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    NTFS compression is transparent. In all but very specific cases, the CPU time overhead is negligible.
    – Daniel B
    Commented Jan 8, 2019 at 19:34
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    The actual answer to this question is here: superuser.com/a/1381546/122639
    – fritzmg
    Commented Jan 11, 2019 at 7:20

4 Answers 4

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use this command in cmd to disable compression

fsutil behavior set DisableCompression 1
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    Use this command sparingly as Windows is auto compressing to prevent the HD maxing out. This is a good thing even if it was done without permission.
    – TravisO
    Commented May 14, 2019 at 13:33
  • I don't see how this is a good thing. Windows does not seem to notify the user. A completely full volume is just delayed, and even worse, compression is not an option any more once the volume is full again.. Commented Sep 23, 2019 at 19:25
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I noticed this happening after my upgrade to Windows 10 version 1809 (the October 2018 update) on my 32GB SSD. I usually save my documents in progress on my Desktop before moving them to their permanent locations, and I saw all of my new files getting the two blue arrows. Checking these files' advanced properties revealed that they are indeed being automatically compressed by Windows. None of the policy settings or registry settings to disable compression are preventing this. If I look at the properties for the whole C: drive it shows that automatic compression is off. But if I look at the advanced properties for C:\Users\myaccount\Desktop and C:\Users\myaccount\Documents I can see that they have been set to automatically compress files. If I uncheck this in the two folders (and choose to apply the change to all files and folders under these) then it does seem to stop this behavior, even after a restart.

I can not find documentation for Windows 10 version 1809 that describes the conditions under which Windows starts automatically compressing files without asking the user for permission to do this. It may have been necessary for the update to version 1809 to have enough space to complete the update, but at no point did Windows ASK me if this was OK. It just did it. Normally this would not bother me too much, but one of the identified flaws early in the release of version 1809 was that zipping of automatically compressed files (for example for the purpose of copying/upload files to other locations off of the computer) caused corruption in these files. So the Microsoft developers have obviously made mistakes in released code as far as compression goes.

I seem to recall a recent version of Mac OS X doing a similar thing in which it started encrypting files without asking after a particular update. This trend is not a good one. Again, at least if Windows had ASKED me before doing this then the sudden compression of my files would not have been a surprise requiring me to seek out answers on the Internet.

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  • I'm surprised that Windows does this automatically, without the courtesy of a notification, and the only thing that indicates anything happened is a non-metaphorical icon.
    – Tim
    Commented Jul 6, 2020 at 21:35
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"128GB SSD and with 5GB free space."

That's why - the drive is choking.
It desperately needs more space so it's got to try to compress absolutely everything it can.

You really need to always have 10% free space, at minimum; preferably 15%.
I'm aim for never showing more than 110GB used, preferably 100GB.

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It seems that, indeed, Windows compresses files and folders when the hard drive is kinda full. Of my 128 GB SSD, I had around 15 GB left and it started compressing everything without asking, resulting in song projects getting corrupted and 100% losing them.
Thing is, it should always ask if you want the system to do this kind of things or you want to do it yourself or it can result in this kinds of situations where someone like me, has lost about a hundred hours of work.
That being said, I can't find where I could deactivate this or at least change the settings.

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