In the end, I want to format an external hard drive. It connects up via cat5 cable to either my MBP or my Airport Extreme. Either way I see it in finder under SHARED just fine. But I can't find it in Disk Utility to format it. I assume that it needs to be in Finder under DEVICES, but I could be wrong. How do I situate the external hard drive so I can see it in Disc Utility? Thank you!