While system restore is a God send it can have a tendency to consume large amounts of disk space. By default System restore is allocated a minimum of 15% of disk volume for restore points.
Decreasing system restore space is somewhat a trade off - reduce the allocated space and, although you gain extra free space, you also loose the earlier system restore points. If you are happy having a reduced number of system restore points available, then by all means reduce the allocated space.
However, before you can make an informed decision as to how much to reduce the space allocated to system restore, it is wise to find out just how much space system restore is actually consuming.
In Windows XP increasing or decreasing the available space to system restore was no more complex than opening the System window in Control panel, clicking the system restore tab, then clicking the settings button and adjusting a slider bar to increase or decrease the space.
In Windows Vista this option has now disappeared. the whole process of enlarging or reducing system restore space has become more complex. Instead of a simple slider bar all such alterations must now be done via command line option.
To see how much space system restore is actually taking up you need to use the Volume Shadow Copy Service Administration Tool (vssadmin, for short), which runs from an elevated command prompt as follows:
1/ Click Start
2/ From the Start menu Click All programs followed by Accessories
3/ On the Accessories menu Right Click on the Command Prompt option
4/ From the drop Down menu that appears, click the Run as administrator option
5/ When the Command Prompt window opens type: vssadmin list shadowstorage and Press Enter
6/ The results should read something like 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{db8e056a-6294-11db-9f9f-806e6f6e6963}\
Shadow Copy Storage volume: (C:)\\?\Volume{db8e056a-6294-11db-9f9f-806e6f6e69
63}\
Used Shadow Copy Storage space: 197.766 MB
Allocated Shadow Copy Storage space: 400 MB
Maximum Shadow Copy Storage space: 2.092 GB
7/ In this example the C: drive is 19.5GB in size. The currently used storage space is 197.766MB and the Maximum space allocated for System restore is 2.092GB.
8/ The current stored system restore points are 2. this can be found out by using the vssadmin list shadows command.
9/ In my opinion the 2.092GB Maximum shadow copy storage space is quite acceptable for this size of partition. However, the larger the drive/partition the more space will, inevitably, be allocated for system restore points.
Reducing the Allocated Space
To reduce the allocated space we need to use the Resize option in the form of:
vssadmin resize shadowstorage /on=[here add the drive letter]: /For=[here add the drive letter]: /Maxsize=[here add the maximum size]
Let us assume that we wished to have a maximum size of 2GB from this particular partition/drive. The command line option would look something like this:
C:\Windows\system32>vssadmin resize shadowstorage /On=C: /For=C: /Maxsize=2GB
So to put this in to practice you proceed as follows:
1/ Click Start
2/ From the Start menu Click All programs followed by Accessories
3/ On the Accessories menu Right Click on the Command Prompt option
4/ From the drop Down menu that appears, click the Run as administrator option
5/ When the Command Prompt window opens type: vssadmin resize shadowstorage /on=[here add the drive letter]: /For=[here add the drive letter]: /Maxsize=[here add the maximum size] and Press Enter
6/ if all goes well you should see a message saying 'Successfully resized the shadow copy storage association
7/ Your System Restore shadow storage has now been resized
