It is possible to reduce disk space used by shadow copy storage if you need to.

Windows uses the Volume Shadow Copy Service to make a copy of your hard drive for restoration from System Restore.Sometimes this can take up too much space, especially if the hard drive is small, so you may need to reduce disk space used by shadow copy storage.

VSS can sometimes make multiple copies of the drive, using up all available space, even though one copy can need as little as 20 – 30GB. Fortunately there are commands to be able to view how much space is currently in use and adjust the amount of space that is allocated to VSS.

Open a command prompt and type the following

vssadmin list shadowstorage

The below will be displayed.

C:UsersUser>vssadmin list shadowstorage

 Shadow Copy Storage association

   For volume: (D:)\?Volume{ }

   Shadow Copy Storage volume: (D:)\?Volume{}

   Used Shadow Copy Storage space: 58.9 GB (3%)

   Allocated Shadow Copy Storage space: 61.7 GB (4%)

   Maximum Shadow Copy Storage space: 100 GB (6%)

Here we can see that 58.9GB is currently used for VSS, 61.7GB has been allocated and 100GB is the maximum space that VSS can use. This value has been changed from the original value in order to limit the space available to VSS, as it was using over 200GB.

The following command limits the size that VSS can use.

vssadmin resize shadowstorage /for=C: /on=C: /maxsize=50GB

Lets break the command down,

vssadmin resize shadowstorage 

This tells Windows that we are resizing the VSS storage space.

/for=C: /on=C: 

This tells Windows that the VSS storage is on the C drive, change the letter to match your environment.

/maxsize=50GB

This tells Windows the maximum size to use for VSS.

For my example, I used

vssadmin resize shadowstorage /for=D: /on=D: /maxsize=100GB

Still within command prompt, type the command below, making sure to change the variables to match your environment and preference.

vssadmin resize shadowstorage /for=C: /on=C: /maxsize=50GB