Today I worked with a customer who was using Data Backup 3 to clone his MacBook Pro's hard drive so he would have a backup that he could use as a startup disk in case his internal drive failed. He had tried the clone a few times but was not able to use this backup drive as a startup disk. He was not sure what he was doing wrong so he contacted support. After working with him we found out that his external drive was using Master Boot Record as the partition scheme and was formatted as FAT-32. This is very common for hard drives sold in stores since mostly they are sold to Windows users. When a Mac person plugs it in, the Mac and read and write to FAT-32 so it seems fine "out-of-the-box" but when you're wanting to use it in a more advanced way (such as making it bootable), you will need to format the drive into a native Mac format. For that reason alone, we always recommend that whenever you buy a hard drive for use on your Mac, that you format it with your mac, using GUID / Mac OS Extended. He would not be able to boot his MacBook Pro using the drive the way it was currently formatted so I worked with him to erase the drive and set it to use GUID Partition Table and format it as Mac OS Extended. Once we had the drive properly formatted he set up a new backup set in Data Backup 3 and ran the clone again. When the backup completed he was delighted to see that it showed up as a Startup Disk in his System Preferences and he was able to restart his MacBook Pro using his clone backup as the Startup Disk.