Sandeep,
The problem is, I believe, is the brilliant idea of forcing a backup to the Backup folder inside the AC folder. Therefore, no matter where he chooses to make a backup, he must back up on the old server with the 100GBs of free space (which should be plenty), which means it will back up to the Amazing Charts folder. I have been trying to find a way to keep it from being backed up there.
O, I get it now. Thanks. So what he's saying is that even with 100 GBs of free space, the backup fails? That's interesting. It could be timing out. Check the event viewer for errors.
Take Bert's initial suggestion of just copying the entire II and images folder. Be sure to make backups.