Disk Quotas

Disk Quotas is a feature of Microsoft Windows Server that administrators can use to track and control disk usage on a per-user basis for each NTFS file system volume that the user stores data on.

What is Disk Quotas?

A feature of Microsoft Windows 2000 that administrators can use to track and control disk usage on a per-user basis for each NTFS file system volume that the user stores data on.

Depending on how disk quotas are configured, when a user exceeds the specified disk limit, one of two things can occur:

  • An event is logged to the system log.
  • Disk access is blocked and an event is logged. The user is presented with an “insufficient disk space” error.

How it works

Support for disk quotas is built into the new version of NTFS on Windows 2000. Disk quotas are tracked independently for each NTFS volume even if several volumes are on the same physical disk. For purposes of managing disk quotas for users, disk space usage is based on file and folder ownership. Windows 2000 ignores compression when it calculates how much disk space a user is utilizing. Whatever is unallocated in a user’s disk quota is reported as free space for applications that allow the user to access disk space.

You use the Quota tab on the property sheet for an NTFS volume to enable disk quotas, set quota limits, and specify what happens when users exceed their quotas. To configure disk quotas for users, you essentially specify two values:

  • Quota limit:
    How much disk space the user is allowed to use


  • Quota threshold:
    The conditions under which an event should be logged to indicate that the user is nearing his or her quota limit


For example, if the quota limit for a user is set to 10 MB while the quota threshold is specified as 8 MB, an event is logged when the user stores more than 8 MB of data on the volume, and the user is prevented from storing more than 10 MB of data on the volume.

To view the status of disk quotas on an NTFS volume for which this feature has been enabled, open the volume’s property sheet and examine the traffic light icon. The light is

  • Red if quotas are disabled
  • Yellow if the NTFS file system is recalculating the status of quota compliance
  • Green if quotas are enabled

Disk quotas are specified on a per-volume basis. That is, disk usage is tracked independently for different volumes.

Graphic D-31. Disk quotas.


If you want to track disk usage by user but don’t want to deny users access to a volume, you can enable disk quotas but specify that users can exceed their disk quota limit. Note also that enabling disk quotas incurs slight overhead in file system performance.

To use disk quotas on an NTFS volume, enable this feature when the volume is created and before any users have access to it. Begin by setting more restrictive settings for all users, and then relax these settings for users who need more disk space or work with large files.