I spoke with a customer who was trying to clone a used volume on his Mac to another external hard drive and was not able to start the clone process. I asked him what the size of the volume is and it showed in Duplicate to be the same size but the target volume was not able to be selected for this process. I explained to the customer that Drive Genius 3 when doing a volume clone both volumes have to be exact same size or the Target volume could be larger. We checked the size of the 2 volumes in Drive Genius 3 info section and found out the destination volume was in fact smaller by 200mb. I worked with him using Repartition in Drive Genius 3 to make the destination drive larger in size by resizing the preceding volume and then adding it to the destination volume. He was happy for the help because this is a easy tool to use but you still have to take some precautions in setting up the volumes and resizing.