Computers running Microsoft® Windows Vista operating systems may experience that the amount of free hard disk space quickly diminishes during normal use of the computer. Users may also receive Low Disk Space warnings. This problem may be caused by the System Restore feature, as the default disk space limit used by System Restore in Windows Vista is larger than in previous versions of Microsoft Windows operating systems. Reducing the amount of space allowed for System Restore can resolve the problem.

The System Restore feature in Windows Vista is a function of the Volume Shadow Copy Service (VSS). By default, System Restore is allowed a minimum of 15% of the total disk space to save restore points. The amount of hard disk space allowed for System Restore can be viewed and changed using the Volume Shadow Copy Service Administration Tool (vssadmin).

To view the amount of disk space used by System Restore, perform the following steps:

1. Open an elevated command prompt.

   Click here to see how to open an elevated command prompt.

   1. Click .

   2. In the Start Menu, click All Programs, then click Accessories.

   3. In the Accessories menu, right-click on the Command Prompt option.

   4. From the drop down menu, click Run as administrator.

   5. Click Continue or Allow in the User Access Control (UAC) pop up window.

2. At the command prompt type:

   vssadmin list shadowstorage

   and press the <Enter> key.

The result will display something similar to this:

C:\Windows\system32>vssadmin list shadowstorage
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2005 Microsoft Corp.

Shadow Copy Storage association
    For volume: (C:)\\?\Volume{5e9e3ba6-7104-11dc-8a9e-806e6f6e6963}\
    Shadow Copy Storage volume: (C:)\\?\Volume{5e9e3ba6-7104-11dc-8a9e-806e6f6e6963}\
    Used Shadow Copy Storage space: 4.93 GB
    Allocated Shadow Copy Storage space: 5.776 GB
    Maximum Shadow Copy Storage space: 21.981 GB

	Note:
	In this example, the C: drive is 146 GB in size. The currently used storage space is 4.93 GB and the maximum space allocated for System Restore is 21.981 GB.

To change the amount of disk space used by System Restore, perform the following steps:

1. Open an elevated command prompt.

   Click here to see how to open an elevated command prompt.

   1. Click .

   2. In the Start Menu, click All Programs, then click Accessories.

   3. In the Accessories menu, right-click on the Command Prompt option.

   4. From the drop down menu, click Run as administrator.

   5. Click Continue or Allow in the User Access Control (UAC) pop up window.

2. At the command prompt type:

   vssadmin resize shadowstorage /On=[drive_letter] /For=[drive_letter] /Maxsize=[disk_space_limit]

   Where [drive_letter] is the drive letter of the hard disk and [disk_space_limit] is the new maximum amount of space for System Restore. For example, to set a maximum size of 2 gigabytes for System Restore type:

   vssadmin resize shadowstorage /On=C: /For=C: /Maxsize=2GB

3. Press the <Enter> key.

	Note:
	Most computers running Windows Vista will use C: for the drive letter, but the drive letters may vary depending on how many hard disks are present.