System Restore disk space usage can be easily configured using the slider control provided in the System Restore settings in Windows XP. But no such GUI option exists in Windows Vista. Windows Vista by default allocates 15 percent of the total drive space or 30 percent of the available free space (whichever is smaller) for Shadow Copy storage. Note that System Restore in Windows Vista is based on Shadow Copy, and thus it gets the allocated disk space information from the Volume Shadow Copy service. (The Previous versions feature use the Shadow Copy, as well.) To view or adjust the disk space allotted to System Restore you need to use the Vssadmin command-line tool included in Windows Vista.

View disk space used by System Restore

To view the used space and maximum allotted space for System Restore, first open an elevated Command Prompt window. To open an elevated Command Prompt, click Start, click All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator. Then type the following command and press ENTER:

This shows the allocated space for Shadow Copy for each drive in the system.

vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool.<br /> (C) Copyright 2001-2005 Microsoft Corp.<br /> Shadow Copy Storage association<br /> For volume: (C:)\\?\Volume{3e4752e9-a341-11db-952e-816e6f6e6963}\<br /> Shadow Copy Storage volume: (C:)\\?\Volume{3e4752e9-a341-11db-952e-816e6f6e6963}\<br /> Used Shadow Copy Storage space: 2.344 GB<br /> Allocated Shadow Copy Storage space: 2.599 GB<br /> Maximum Shadow Copy Storage space: 3.662 GB<br />

Note: If you use a non-elevated Command Prompt window to run vssadmin.exe, you’ll see the following error message:

Reducing the disk space allocation for System Restore

The default values would be sufficient enough for most people and needs no alteration, as most systems nowadays come with large capacity hard drive. If you have a small hard drive and you’re running out of disk space, then you may reduce the disk space used by System Restore using the vssadmin resize shadowstorage command. The syntax is given below:

MaxSizeSpec must be 300MB or greater and accepts the following suffixes: KB, MB, GB, TB, PB and EB. If a suffix is not supplied, MaxSizeSpec is in bytes. If MaxSizeSpec is not specified, then there will be no limit to the amount of space it may use.

IMPORTANT: Resizing the storage association may cause shadow copies to disappear. And, setting the MaxSizeSpec value less than 300 MB will wipe out all the shadow copies, and thus clears out all the System Restore points.

EXAMPLES

To allot Shadow Copy 2 GB of space for C: drive, use this command:

To allot Shadow Copy 700MB of space for C: drive, use this command:

After running the command, you should see the message Successfully resized the shadow copy storage association in the Command Prompt. Optionally, you can verify the allotted space by running the vssadmin list shadowstorage command.