While creating a dualboot VM (to test dual booting operating systems before doing it on a real machine), I looked at the Task Manager. This was the disk usage shown in the Overview tab. Disk Usage (50%)

This was the Performance tab, a few seconds later.

Disk Usage (100%)

I can't think of any reason this would be, except that it is combining the disk usage for hard disk C: and USB drive E: (But this would not be the problem, as it sometimes shows the Overview disk usage at 100% with both drives plugged in (and Disk E: inactive), too).

Is this a Task Manager glitch, or something else I have not thought of?

2 Answers 2


That main window combines the disk usage of the two as you said.

I't doesn't seem to care whether or not the other drive is being used and it will always base the percentage depending on how many drives you have. in my case i have 3 drives and thus the main window will judge each drive on a scale of 33% each. if only one drive is handling operations in that moment then 33% will be the max usage reported for that drive, if two then 66% etc.

this is the epitome of stupidity by Microsoft as common sense would have indicated a person uses the task manager for a more in depth analysis of what's going on with their system, combining the usage of our drives isn't the smartest move. also there is no option to select if you want it to show usage per disk or not


You can try some of these solutions: https://windowserrorfix.org/100-disk-usage-windows-10-fix/

This may also happen because the speed of your disk is low. When creating a VM, you need to maintain the host and virtual system simultaneously and this can lead to high disk usage. As for the use of disk E: when it is not being used it may be due to some Windows problem.

  • 100% disk usage is from the VM's install program, so that article doesn't apply to my issue. I (now) specified E: is a USB flash drive, so it would be normal for it to be inactive. (This answer also does not explain the 50% and 100% disk usage at the same time).
    – Zackary
    Apr 25, 2018 at 19:03
  • 1
    A hint: Do not reply with an URL, put here what the URL says about it. Apr 25, 2018 at 19:53

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