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

Note: Partitioning your hard drive with Disk Utility or Drive Setup requires that you initialize it, a process which will erase all the information on the drive. Be sure to back up all the important files you wish to keep before using these directions.

To partition your hard drive, boot from a Mac OS or Mac OS X install disc. To do this, insert the disc in the drive and restart the computer while holding down the  c  key. When you see the gray Apple or Happy Mac icon, you may release the  c  key.

Mac OS X

Note: The following assumes you are using Mac OS X 10.1 or later.

If your install disc is for Mac OS X, follow these steps:

1. From the Installer menu, select Open Disk Utility... . In the window that opens, on the left, click the icon for the drive you would like to initialize or partition.
   
   
2. To the right, click the Partition tab.
   
   
3. In the pop-up menu under "Volume Scheme:", choose the number of partitions to be created during the initializing process. By partitioning your drive, you divide it into multiple volumes that can hold different file and operating systems. For a basic installation of Mac OS X, just one partition is necessary.
   
   
4. After you've chosen the number of partitions you want, you can adjust their sizes by dragging the graphical handles that represent the partition borders.
   
   
5. Click each of the partitions to adjust its properties. Under "Volume Information", you may choose the format you would like to use. The default choice will be Mac OS Extended or Mac OS Extended (Journaled), depending on the version of the operating system you have, and typically it should be the one you use.
   
   
6. Once you've chosen your volume scheme, click the Partition button.

After your drive is formatted and partitioned, you may continue with other installations from your install disc. Of course, such an installation will be necessary before you can boot (start up) from your newly partitioned hard drive.

Mac OS 7.5.x through 9.x

If your install disc is for Mac OS 7.5.x through 9.x, follow these steps:

1. When the Mac OS install CD opens, double-click the Utilities or Disk Tools folder. If you see a Drive Setup folder, open it. Next, double-click the Drive Setup application. The main Drive Setup window will open.
   
   
2. In the Drive Setup window, under "List of Drives", choose the volume (hard drive) you would like to partition.
   
   
3. Click the Initialize... button, then click the Custom Setup... button.
   
   
4. In the Custom Setup window that opens, click and hold on the contextual menu next to "Partitioning Scheme:" Here, you may choose the number of partitions that will be created during the initializing process.
   
   
5. After you've chosen the number of partitions you want, you can adjust their sizes by dragging the graphical handles that represent the partition borders.
   
   
6. Under "Volumes", click each of the partitions to adjust its properties. Under "Volume Info", next to "Type:", you may choose the file format you would like to use. In recent versions of the program, if you are going to be installing Mac OS or Mac OS X, choose one of the following:
   
   
   • Mac OS Standard (HFS)
   • Mac OS Extended (HFS+)
   • Mac OS UFS
   
   
7. Once you've chosen your partitioning scheme, click the OK button. Then, click the Initialize button.

After your drive is formatted and partitioned, you may continue with other installations from your Mac OS install CD. Of course, such an installation will be necessary before you can boot (start up) from your newly partitioned hard drive.

Also see:

• In Mac OS X, why can't I unmount my drive to initialize it?
• In Mac OS X, what is First Aid, and when and how should I use it?
• On my Macintosh computer, why can't I format or partition the internal hard drive?