VSS is a great feature, but you could find that the files for which you want to restore previous versions are not always available. A common reason for this is that there simply is not much space dedicated to VSS and it overwrites reguarly when it runs out of this space. VSSadmin.exe lets you view many aspects of your VSS configuration. To resize the maximum size for a shadow copy storage, this command line utility may also be used to get the job done.

vssadmin Resize ShadowStorage /For= /On= [/MaxSize=]

Use the For argument to specify what volume you wish to have VSS support. The On argument lets you specify on which volume you'd like the shadow placed- this can be the same drive or not. For servers it is a good practice to dedicate a volume to this purpose and resize it to take advantage of the entire space allotted. The MaxSize parameter should be used to specify the maximum size. It must be at least 300MB, but you can also specify suffixes like KB, GB, TB and PB so if you had a dedicated volume you might say MaxSize=80GB. If you just list a number here with no suffix, the size will be assume to have been provided in bytes (so be sure to specify!)

Example Usage:

vssadmin Resize ShadowStorage /For=C: /On=D: /MaxSize=40GB