How to Format a Disk Drive on Mac OSX
Formatting a drive is really simple, however the #1 thing to remember is that you must select the correct partition map scheme! Apple will screw you here when you try to upgrade your OS.
Let me explain, in order to upgrade Mac OSX between major versions, an Intel based Mac must have an GUID Partition Table on the boot drive. I was put into a bind recently, when I swapped harddrives, and formatted the new hard drive with the default setting, Apple Partition Map. This restricted me from upgrading that hard drive on Snow Leopard.
Step 1 - Launch Disk Utility
You can start Disk Utility one of two ways. Either by opening Spotlight (Command + <Space Bar>) or by going to your applications folder and opening Disk Utility.
Step 2 - Choose the HardDrive you want to Format
IMPORTANT: Make sure to choose the correct disk drive. If your hard drive is an external, it will usually be indicated by a little orange USB Drive icon or Firewire icon. For each hard drive connected to your computer there are 2 listings per diskdrive. This is because the top listing refers to the Hard Disk Drive itself, the listing below is the 'partition' on your hard drive (usually just one). Learn more about disk partitioning on wikipedia.
Step 3 - Set your Format Options
After selecting your hard drive, click the 'Partition' tab at the top, after 'Erase', then click 'Options' to open the Hard Drive Partition Scheme configuration screen.
IMPORTANT: If you plan to use this drive as a Master Boot drive in an Intel Mac OSX Computer, such as a MacBook, or iMac, or Mac Mini, Select 'GUID Partition Map'. The other formats might work to boot, but Apple will not allow you to upgrade the OS!
Mac OSX Formatting Options
Choose a partition scheme appropriate for the way you will use this disk:
- GUID Partition Table (recommended) - To use the disk to start up an Intel-based Mac, or to use the disk as a non-startup disk with any Mac with Mac OS X version 10.4 or later.
- Apple Partition Map - To use the disk to start up a PowerPC-based Mac, or to use the disk as a non-startup disk with any Mac.
- Master Boot Record - To use the disk to start up DOS and WIndows computers, or to use with devices that require a DOS-compatible or Windows-compatible partition.
IMPORTANT: Make sure to choose the correct disk drive. If your hard drive is an external, it will usually be indicated by a little orange USB Drive icon or Firewire icon. For each hard drive connected to your computer there are 2 listings per diskdrive. This is because the top listing refers to the Hard Disk Drive itself, the listing below is the 'partition' on your hard drive (usually just one). Learn more about disk partitioning on wikipedia.
Step 3 - Set your Format Options
After selecting your hard drive, click the 'Partition' tab at the top, after 'Erase', then click 'Options' to open the Hard Drive Partition Scheme configuration screen.
IMPORTANT: If you plan to use this drive as a Master Boot drive in an Intel Mac OSX Computer, such as a MacBook, or iMac, or Mac Mini, Select 'GUID Partition Map'. The other formats might work to boot, but Apple will not allow you to upgrade the OS!
Mac OSX Formatting Options
Choose a partition scheme appropriate for the way you will use this disk:
- GUID Partition Table (recommended) - To use the disk to start up an Intel-based Mac, or to use the disk as a non-startup disk with any Mac with Mac OS X version 10.4 or later.
- Apple Partition Map - To use the disk to start up a PowerPC-based Mac, or to use the disk as a non-startup disk with any Mac.
- Master Boot Record - To use the disk to start up DOS and WIndows computers, or to use with devices that require a DOS-compatible or Windows-compatible partition.
Step 4 - Choose options
The green arrow highlights the different formatting options you can choose. I recommend Mac OS Extended Journaled, as that applies to most applications. If you need the drive to be used alongside Windows or DOS machines, you may want to select FAT formatting. You can choose to create one giant partition, or multiple partitions. Most likely you just want 1, more than 1 is for advanced situations, such as dual booting, so if you're not sure leave it with one partition at the full disk size.
Click the 'Apply' button and you're done! It should just take a few seconds.
If you have any questions about erasing your drive, be sure to read our Secure Disk Drive Erase Mac OSX Tutorial.
