Most drives come set up for Windows, and while they’ll generally work with the Mac, they won’t work properly as startup drives.
A “partition scheme” is the low-level on-drive stricture that is used by the OS to find the “volumes” (the “drives” that appear in Finder—a physical disk can have one or more) on a physical disk. There are three different “partition schemes” that can be used on the Mac:
* Master Boot Record—this is the partitioning scheme used by Windows, and how most drives are shipped.
* Apple Partition Map—the original partitioning scheme used by the Mac, required for Power PC based Macs.
* GUID (aka GPT)—the new partitioning scheme used by Intel Macs.
So, here’s what you should do with a new drive.
- Start Disk Utility (it’s in /Applications/Utilities)
- Select the external drive hardware in the sidebar.
You must select the drive hardware, above any existing volumes, or the Partition tab will not appear.
- Click the Partition tab
- Use Disk Utility’s controls to divide the drive as needed, even as a single large partition. Use “Mac OS Extended (Journaled)” as the format type and name appropriately
- Click the Options button
- Choose the proper partition scheme (GUID for Intel macs, Apple Partition Map for Power PC) and accept the page
- Click Partition.
I use the Drobo as a bootable backup and it works fine. You have to format the Droba via Disk Utility and not via Dashboard. Only in DU can you set it as “GUID”