When you install new software programs, patch existing ones or update drivers on your computer, Windows will automatically store a snapshot of your system before making the changes. This helps because if something stop working after the installation, you can easily restore your system to the previous working state.
Other than system files, Windows also stores backup copies of data files (like documents, pictures, etc.) on your computer which may come really handy if you accidentally modify or delete the original files. Technically, these are known as shadow copies and the feature is available in all editions of Windows Vista and Windows 7.
If you have been using your computer for some time, the disk space consumed by these restore points and shadow copies may easily run in gigabytes (see the size of the “System Volume Information” folder on your C: drive).
You have two options for reclaiming this space – you can either remove all the restore points from your system or, if you would like to play extra safe, you can keep the new restore points and just get rid of the old ones.
Step 1: Disk nearly full? Free-up some space..
Click the Windows Start button and type cmd in the search box (not the Run dialog). Now press Ctrl + Shift + Enter to open the command prompt with Administrator privileges. Click Yes if you are shown the User Access Control Window.
Now type the following command to remove only the old shadow copies:
c:>vssadmin delete shadows /for=c: /oldest
Or, if your system is working normally, use this command to remove all the shadow copies.
c:>vssadmin delete shadows /for=c: /all
Refer to Microsoft Technet for more details on the VssAdmin command.
Step 2: Why reserve less space for shadow copies..
Windows will continue to save new restore points until all the reserved disk space is filled up. That means if you have less reserved space, the old ones will get deleted more quickly as new ones are created.
Go to Windows Start –> Run and type sysdm.cpl to open the System Properties dialog. Click the “System Protection” tab and choose Configure.
If the disk space allocated for system protection is on the higher side, you may move the “Max Usage” slider to the left and set it anywhere between 3% and 5% of the total disk size. The reserved space should also be greater than 300 MB according to Windows help.
Step 3. Make a fresh start..
Now that you have recovered some important space, go back to the “System Protection” tab and click Create to to capture of snapshot of your system in its current working state – just to be on the safe side of things.
Related: If you are on Windows Vista, you may also use the Vista Cleaner utility to free some more space on your system