[Value data type] REG_DWORD [Description] If this policy value is set to a value greater than 0, Windows Installer saves old versions of patched files in a cache. Set the value to the maximum percentage of disk space that can be used for the file cache. For example, a value of 15 and sets the maximum to 15%. Set to 0 to save no files. When this policy is not set, the default is 10%. [Policy] 
MaxPatchCacheSize