/For=ForVolumeSpec /On=OnVolumeSpec /MaxSize=MaxSizeSpec - Adds a shadow copy storage association between the volume specified ...

%1 %2 /For=ForVolumeSpec /On=OnVolumeSpec [/MaxSize=MaxSizeSpec]     - Adds a shadow copy storage association between the volume specified by      ForVolumeSpec and the volume specified by OnVolumeSpec the shadow copy     storage volume.  Storage for shadow copies of ForVolumeSpec will be      stored on OnVolumeSpec.  The maximum space the association may occupy on      the shadow copy storage volume is MaxSizeSpec.  If MaxSizeSpec is not      specified, there is no limit to the amount of space may use.  If the      maximum number of shadow copy storage associations have already been      made, an error is given.  MaxSizeSpec must be 300MB or greater and      accepts the following suffixes: KB, MB, GB, TB, PB and EB.  Also, B, K,      M, G, T, P, and E are acceptable suffixes.  If a suffix is not supplied,      MaxSizeSpec is in bytes.        Example Usage: vssadmin Add ShadowStorage /For=C: /On=D: /MaxSize=900MB