Is there a way I can clone my Macintosh HD to my external hard drive through the disk utility? I am guessing that partitioning my external hard drive into 2 volumes will enable me to keep my original data on 1 volume and creating another for the Macintosh HD. Would this work without losing original data on my external hard drive? I want to back up my iMac and erase all the data after so I can do a new re installation from the Mac OSX install disk. Any advice? Thanks