Give others easy access to shared files. Boot into different operating systems. Back up files without breaking a sweat. Run disk utilities on the road—no CD required. Speed up Photoshop and games galore. Are these merely geek dreams? No, this can all come true for you—without your spending a dime—if you partition your hard disk.
It’s easy to split your Mac’s hard disk into several partitions with Apple’s free Disk Utility. If you instead use the iPartition utility, you may not have to wipe your hard drive in the process. Partitioning can make your work easier, faster, and safer.
The Many Joys of Partitioning
Here are a few excellent reasons to partition your hard disk:
Easy Access to Backups
Disk problems usually affect the disk’s catalog (an invisible file that records the locations of your files on the disk). If you use a second partition to store backup files, they will be readily accessible if your everyday partition bites the dust. (Of course, if a physical problem causes the entire hard disk to crash—say, if its heads or platters meet their maker—you may also lose your backup partition. Make sure you back up its files regularly, too.)
Quick Backups of Critical Files
You can make quick backups of in-progress work on your extra partition. Simply drag files or folders to it throughout the day. This is an easy way to protect important data as you work. (The same caveats about potential problems with the physical disk apply here.)
A Manageable Home Folder
Store your iTunes or iPhoto collections on a separate partition to make your Home folder smaller and more manageable. This will make the folder easier to back up, though you’ll still want a backup of your media files.
Stress-Free Shared Files
Tired of running into permissions problems when you share files with other users on your Mac? Use a partition to give others easy access to shared files. When you create a partition for this purpose, select it in the Finder, press Command-I, click on the Ownership & Permissions triangle, and then select Ignore Ownership On This Volume. This allows all users to access the files it contains, regardless of the permissions set for the individual files.
Create an emergency partition for those times when bad karma comes home. Use a program such as Bombich Software’s Carbon Copy Cloner (donations accepted) to make a bootable copy of your startup volume on this partition, and install a disk-maintenance and -recovery program such as Alsoft’s DiskWarrior ($80) or Micromat’s TechTool Pro ($98). If you have problems with your startup volume—due to either disk-catalog problems or rogue software that has damaged your operating system—you can simply boot from your emergency partition. To do so, hold down the option key at startup to select the partition, and then run your disk-recovery software—no fumbling around to find CDs. Even if you’re on the road, you can get your Mac up and running again.
Some programs, including Adobe Photoshop, Apple Final Cut Pro, and other audio and video programs, run faster if you store their files on a dedicated partition. Why? Because Photoshop writes scratch files —temporary files—to your hard disk, and these files can be big. Video files likewise take up a lot of disk space. In both cases, using a dedicated partition keeps these files together, allowing the programs to load, read, and write the files quicker. And gamers may want to install games on a separate partition. Some games, especially those with lots of video and graphics, run faster this way, because their files aren’t strewn across a crowded primary partition.
You may have heard that creating a partition for OS X’s swap files will speed up your work, but it won’t really make much of a difference. You’d see a speedup if you stored the swap files on a different physical disk, but if you simply store them on another partition on the same disk, your hard disk’s heads will jump from one section of the disk to another to read them. You may even find that your Mac runs slower.
Easier OS Upgrades
When installing a new version of OS X, do so on a second partition. This is useful when you’re not sure you want the update, as well as when you want an easy way to copy your Home folder’s contents after a clean install.
Linux and More
For the truly geeky, a partition is a great place to house other operating systems. Install Linux on a partition so you can try out your favorite distro on your Mac. If you have an older Mac and still use OS 9 for running some programs or for specific hardware that isn’t OS X-friendly, put OS 9 on a partition so you can boot from it more easily. If you develop software, put different versions of OS X on different partitions and boot from them to test your work in progress. Choose the partition you want to use by holding down the option key at startup.
Old Mac Aid
Finally, if you have an older Mac, such as a rev. A, B, C, or D iMac or a beige Power Mac G3, you must install OS X in the first 8GB of the hard disk. If your hard disk is larger than 8GB, you’ll need to create at least two partitions: a boot partition that is 8GB or smaller, and one or more other partitions that take up the remainder of the hard disk.
Roll Up Your Sleeves and Slice That Disk
Partitioning a hard disk in OS X is not rocket science, but you do need to take precautions. First and foremost, back up your files. Partitioning a hard disk with Apple’s Disk Utility deletes everything on the disk, so make sure you have a complete copy. Ideally, the best time to partition is when you get a new Mac or a new hard disk, since you won’t have to back up anything.
Next, you need to determine whether you’re partitioning your startup volume or another disk—for example, a second internal hard disk or an external hard disk. In each case, you can use Disk Utility to partition your hard disk, but you must launch the program differently. If you want to partition your startup volume, reboot your Mac from an OS X installation CD. Hold down the C key during startup to launch the installer on the CD, and then select Installer: Open Disk Utility. To partition an external disk or a second internal disk, just open Disk Utility (located in /Applications/Utilities).
How Many, How Big?
Click on the disk icon on the left side of the window, and then click on the Partition tab. Unless you’ve already partitioned the disk, you’ll see one partition. Select the number of partitions you’d like to create from the Volume Scheme pop-up menu. They’ll all be the same size unless you click on one to select it, enter a name, choose a format, and select the partition size (See screenshot). Consider allocating about 20GB for the startup partition; as for the others, consider how you’ll be using them to choose a size.
If you have a Mac that can boot into OS 9, and you want to be able to do so, make sure you select Install Mac OS 9 Disk Drivers. You won’t see this option on recent Macs. Once you’ve got everything set up, click on the Partition button. Disk Utility erases the disk and creates the new partitions. When it finishes, quit Disk Utility and restart your Mac.
If you’ve partitioned a disk other than the startup one, you’ll see the volumes appear on your desktop or in the Finder window toolbar immediately. If you partitioned your startup disk, the partitions will appear the next time you restart your Mac.
Many Disks from One
Partitioning your hard drive can provide extra speed, security, and flexibility at no extra cost. You can better organize your files, give applications more elbow room, and have a super-duper emergency partition that guarantees you’ll always be able to boot your Mac.
If you have an enormous hard disk filled with data, think twice before using Apple’s Disk Utility to partition it and erase all its contents in the process. A program such as Coriolis Systems’ iPartition ($45) can create and resize partitions without erasing your hard disk. This can be a big time-saver, since you won’t need to recopy all your data. And it’s great if you’d like to resize partitions later.
iPartition gives you visual information about your disks and partitions, lets you resize partitions by dragging the pieces in a pie-chart display, allows you to add and delete partitions, and offers an abundance of formatting options. In fact, iPartition is one of the few OS X programs that allows you to format disks using dozens of file systems, including FAT, Linux, NTFS, Next, OS/2, and others.
Still back up all your files first. All it takes is a power outage while the program is working, and you’ll lose everything. Also keep an eye out for Micromat DiskStudio ($50), which should be available by the time you read this.
[ Kirk McElhearn is the author of many books, including The Mac OS X Command Line: Unix under the Hood (Sybex, 2004). ]Apple’s free Disk Utility can slice up your hard disk with just a few clicks.