When free disk space on your computer falls below a specific level (threshold), you may receive the following message or one similar to it:

   Hard Disk is Low on Disk Space
   You are running out of disk space on drive C.
   To free space on this drive by deleting old or unnecessary files, click
   Disk Cleanup.
				

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This behavior can occur if the free disk space on your computer has dropped below the low disk space notification threshold associated with the Disk Cleanup utility.

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To resolve this behavior, either click Cancel to close the message, or click Disk Cleanup to start the Disk Cleanup utility.

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This behavior is by design.

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The Microsoft Windows 98 Resource Kit, page 421, states that "The threshold is 25-65 MB, depending on the volume size."

The following table describes these thresholds in more detail:

Disk Size   Threshold    Threshold
            Percentage   Space
----------------------------------------
<= 512 MB   10.0         25.6 - 51.2 MB
<=   1 GB    5.0         25.6 - 51.2 MB
<=   2 GB    2.5         25.6 - 51.2 MB
<=   4 GB    1.2         24.6 - 49.15 MB
<=   8 GB    0.6         24.6 - 49.15 MB
<=  16 GB    0.3         24.6 - 49.15 MB
<=  32 GB    0.2         32.8 - 65.5 MB
>   32 GB    0.1         32.8 - ???? MB
				

For example, if you have a 2 gigabyte (GB) hard disk, you receive the "Hard Disk is Low on Disk Space" message when your free disk space is less than 51.2 megabytes (MB), or 2.5 percent of your total disk space.

These thresholds are not configurable.

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