Basics4Mac - Securing Your Data: Partitioning Your External Drive

Security Series

Partitioning a Hard Drive
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When you buy an external hard drive it will no doubt be larger than the hard drive in your Mac. You can plug it in right out of the box and have a perfectly good large hard drive.

But if your external hard drive is several times larger than your internal hard drive, you might want to consider partitioning it into two or more partitions. Partitioning your drive means dividing it into sections that your Mac will see as separate hard drives. That way you can do a full backup onto one partition, use another for Time Machine, and another for file storage.

You need to partition your external hard drive before you add any files to it. Partitioning a drive deletes all the data on it. Here is how to partition you new external hard drive:

Make sure your hard drive is plugged in and turned on.
Open Disk Utility. It is located in the Applications > Utilities folder.
Select your external hard drive in the sources list on the left. (The icon for the external drive will be orange.)
If you selected the drive properly, a new tab "Partition" appears on the right side. Choose the Partition tab. (Note: if you selected your internal hard drive by mistake, all the buttons and options will be greyed out. You cannot partition the drive you have started your Mac from.)
The simplest way to make partitions is to use the drop down menu under "Volume Scheme". You can select the number of partitions you want and your hard drive will be divided into that many equal sized partitions.
Once you have set up the partitions, you can click on them and give them meaningful names in the Name field.
IMPORTANT: Before you create the partitions, click the Options... button. If you have an Intel Mac, make sure that GUID Partition Table is selected. If you have a Power-PC Mac, make sure Apple Partition Map is selected. (If you don't know which kind of Mac you have, go to the Apple Menu and choose "About this Mac." Then click the More Info... button. In the Hardware Overview you will see either Intel or PowerPC.)
Once you have named your partitions and set the Options, click the Apply button (Partition button in Tiger).

Your partitions will be created and will mount in the DEVICES section in the Finder (left pane in Tiger).

Upcoming tips will talk about what to do with these new partitions you have created.

Advice: If you want to partition your external hard drive, but don't feel comfortable doing it yourself, consider Live Help by Telephone from Basics4Mac.