What is the shadow copy?
The Volume Shadow Copy Service (VSS) is a set of COM interfaces that implements a framework to allow volume backups to be performed while applications on a system continue to write to the volumes.
Is your C: drive full and you need to open up space? Follow the below instructions.
1: Open up command line.
2: type vssadmin list shadowstorage
This will list the list shadow copy storage associations.
3: vssadmin resize shadowstorage /on=C: /For=C: /MaxSize=5GB