ARCHIVED: In Mac OS X, how do I partition my hard drive?

Warning: In versions of Mac OS X prior to 10.5, or when changing the partition scheme in Mac OS X 10.5 and later, partitioning your hard drive with Disk Utility erases all the information on the drive. Regardless of your operating system, UITS recommends backing up all of your important files before partitioning your drive.

Mac OS X 10.5 and later with no changes to the partition scheme

  1. In the Applications folder, open Utilities, and then double-click Disk Utility.
  2. In the left column, click the drive you would like to initialize or partition.
  3. To the right, click the Partition tab.
  4. The box beneath "Partition Layout" or "Volume Scheme:" (which should be set to Current) represents your hard disk, where occupied space is shaded. With the handle at the bottom-right of each partition, you can resize the partition by dragging the handle up or down. To add or remove partitions, click the + (plus sign) or - (minus sign) beneath the box. You can assign each partition its own name and file system type.
  5. When you're finished making changes, click Apply.

Mac OS X 10.4 and earlier, or 10.5 and later with changes to the partition scheme

Open Disk Utility via one of the following methods:

  • In Mac OS X 10.7, to partition your startup disk, restart your computer while holding down Command-r. When you see the gray Apple logo, release the keys. If you see a screen asking you to select your main language, choose it and then click the arrow. Click Disk Utility and then click Continue.
  • In Mac OS X 10.6 or earlier, to partition your startup disk, insert a Mac OS X install disc in your computer, and then restart the computer while holding down the c key. When you see the gray Apple logo, release the c key. Follow the instructions until you see a menu bar at the top of the screen, and then from the Utilities menu, select Disk Utility.
  • To partition disks other than your startup disk, from the Finder, click Go, and select Utilities. In the Utilities folder, double-click Disk Utility.

Once Disk Utility is open:

  1. In the left column, click the drive you would like to initialize or partition.
  2. To the right, click the Partition tab.
  3. In the drop-down menu under "Partition Layout" or "Volume Scheme:", choose the number of partitions you want to create during the initializing process. For a basic installation of Mac OS X, you need at least one partition.
  4. Adjust partition sizes by dragging the handles that represent the partition borders.
  5. Click each partition to adjust its properties. Under "Partition Information" or "Volume Information", choose the format you would like to use. You will normally want to use Mac OS Extended (Journaled). If you need to access the partition from Windows computers, however, choose MS-DOS.
  6. Click Options... to change the partition scheme. You may need to change this if the disk is meant to be used with Windows computers, or as a startup disk for a Mac with a different architecture. Intel Macs require the GUID Partition Table for their startup disks, while PowerPC Macs use Apple Partition Map. If you need to use the disk with Windows, particularly as a startup disk, choose Master Boot Record. After selecting a scheme, click OK.
  7. When you're finished making changes, click Apply or Partition.

This is document ajxz in the Knowledge Base.
Last modified on 2012-12-05 00:00:00.

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