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Volume Shadow Copy Service (VSSadmin)
Windows 7 and Windows Vista come with a command "vssadmin" for administering and configuring the shadow copies provided by System Protection. Its use is described.

Commands available with VSSadmin

VSSadmin comes with a suite of associated commands. Table I lists the commands and their function. Vista Home Premium lacks some of these. The commands may have additional switches. Note that this command should be run as an administrator.

Table I. Commands with VSSadmin
Command Description
Vssadmin delete shadows Deletes volume shadow copies
Vssadmin list providers List registered volume shadow copy providers
Vssadmin list shadows List existing volume shadow copies
Vssadmin list shadowstorage List volume shadow copy storage associations
Vssadmin list writers List subscribed volume shadow copy writers
Vssadmin resize shadowstorage Resize a volume shadow copy storage association
Vssadmin list volumes List volumes eligible for shadow copies

Control the space used by shadow copies with VSSadmin

There are several applications of VSSadmin that might be encountered by an average PC user. One would be to determine how much space is being used by volume shadow copies and another would be controlling how much space is used. Here are the commands and requisite syntax.

Find out how much space shadow copies occupy

To find out how much space System \Restore is using, open the command prompt as administrator and enter

vssadmin list shadowstorage

Reduce the space used by System Restore with VSSadmin

System Restore can use up to 15% of a hard drive for its backup files (shadow storage). As hard drives get ever bigger, that becomes a lot of space. The command "vssadmin" can be used to administer settings for System Restore. To control the space allocation, open a command prompt with administrator privileges and enter vssadmin Resize ShadowStorage /For=C: /On=C: /Maxsize=[n] For [n] enter the desired size in MB or GB. The units must be stated: for example, "Maxsize=500MB" or "Maxsize=2GB". The example is for the C: volume but other volumes can be specified. WARNING! This will delete all your old Restore Points!

Delete shadow copies

If for some reason, you wish to delete shadow copies, here are some options.

vssadmin Delete Shadows /For=VolumeSpec [/Oldest] [/Quiet] vssadmin Delete Shadows /Shadow=ShadowID [/Quiet] vssadmin Delete Shadows /All

Table II explains the various switches and syntax.

Table II. Syntax for deleting shadow copies
Parameters Description
For=VolumeSpec Specifies the volume for which the shadow copy is to be deleted
/Oldest Deletes only the oldest shadow copy.
/Quiet Keeps the command from displaying messages while it is running
/All Deletes all of the shadow copies for the specified volume
/shadow=<ShadowID> Deletes the shadow copy specified by ShadowID. To get the shadow copy ID, use the "vssadmin list shadows" command. When you type a shadow copy ID, use the following format, where each X represents a hexadecimal character: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX

Here is an example command. It deletes the oldest shadow copy on the C: volume.

vssadmin Delete Shadows /For=C: /Oldest

In general, care should be exercised when deleting shadow copies.

VSSadmin in Windows XP

If you look, you can find VSSadmin in the command line for Windows XP Professional but it isn't of any great use there.

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