This is a Two Stage Process
1) The Shadow copy components is first 'exported' to some files on the disk.
2) Then these files are backed up
The Shadow copy components is like a running database , We cannot backup a running database just by coping the files. So, the data in the Shadow Copy Component is 'exported' to flat files in a form that it can be restored from. This flat file are created on the disk , then writes these flat files to tape.