Question: I wonder if I need to keep all my things organized in one volume or if I should partition my drive. What are the advantages of partitioning? Should I do it?
Answer: I am aware that partitions usually bring a debate, but I am confident enough to give you a resounding YES.
The way your Mac handles files is a bit messy. As data changes through daily use, photos, text files and other things get tangled up with your system files. Despite Mac OS X’s default defragmentation work, this is a problem for disk performance and, inevitably, system performance at large.
Partitions provide an answer if you use them to separate types of data. How to do it? Most people should be content with a startup partition to host their system and a partition for data. Power users can go further with a more complex organisation system, but they are not the ones I target with this article.
What you gain
The process takes a few hours but there are long-term gains associated with it.
The first is to minimize disk strain for daily use. Your system partition is the one that handles the harder work and it has the space to do it on its own. It doesn’t need to mess with your data anymore.
Secondly, this makes data backups and disk optimization simpler. This makes it more interesting to perform such operations more often, reducing your risk having an outdated backup to recover from a disk crash. Freelancers who need their Mac as a work tool make the biggest gain here.
Finally, there is a structure issue. A common data loss cause is related to file structures that get messed up. Separating your types of data helps keep cleaner structures, reducing your risk.
Please note that partitions do not prevent a disk crash.
How to do it
Before you start, I believe that for the sake of keeping your data safe, you should work with an external disk drive that you normally use as a bootable backup. This is where you normally clone your internal disk with Carbon Copy Cloner or SuperDuper. Read Mac Support Central’s entry about backups for reference if you are not famililar.
Step one: calculate your data use
In the Finder, create folders where you place your photos, videos, text and other files that count as data. These files you will later put in your data partition. Use the Get Info (Command and I on the keyboard) to calculate the sizes of those folders. Make a note about the combined size in gigabytes.
Once data is excluded from them, use Get Info again to calculate the sizes of the following folders: Applications, Developer, Library, opt, System and Users. Make a note about the total combined size.
Step two: create your partitions externally
You first need to partition and erase the external drive to mirror what you will do on your internal disk. Launch Disk Utility, which is located Applications > Utilities folder. Once you have its main screen, click on the disk icon that starts with the size and brand, and this will bring a number of tabs. One of them is the Partition tab. Click on it.
Under Volume Scheme, make sure to select 2 partitions instead of Current. If you use virtualization software to use Windows or Linux, choose 3 partitions.
1- System partition
Select the partition on top and give it a name with Mac OS Extended format. Notice that you can attribute a specific size to it, either by inserting a number manually or resizing. What kind of space should you give it? It goes with use.
This is where you will store system software, your applications, preference files, user folders and so on. This is everything that your system contains Mac OS X and software you typically add. Wit all of this under Snow Leopard, I have around 36 GB of files on it once data files are separated.
If you have something of that type, I strongly suggest that you give this partition some elbow room to install more applications and handle future growth. If you also have around 36 GB, give it around 60 GB or a bit more. Adjust according to your use of space and disk size.
2- Data partition
Click on the second partition below.
This is where you will store photos, video, music, general documents and whatever else. You may want to give this partition the most space to both store ever-expanding data and use it as a scratch disk for applications like Photoshop. Power users may just create a scratch disk partition.
3- Windows/Linux partition (optional)
If you are one of these people who use Windows/Linux on their Mac, you will click on the third partition. Look at the hard drive requirements for your virtual system and give yourself some elbow room on the partition. In the case of a Windows install, make sure to click on the Options button when this partition is selected. This allows you to select the Master Boot Record option you need to be MS-DOS compatible.
Step two: erase!
You have set up partitions. Erase your disk. Don’t freak out while it happens :-)
A few moments later, the new partitions will appear on your desktop.
Step three: time for some cloning
This is where you will create your new disk’s mirror. Launch Carbon Copy Cloner or Super Duper and use it to clone your internal drive on the system partition. Do this while excluding the data file folders that you separated previously. Again, check out our guide about using cloning software if you are not familiar.
Once you are done cloning, simply drag your data folders from your internal drive to the data partition which you can find on the desktop. This will copy your data to the external disk.
You now have an external disk which is set up with your new partitions, and your files have been copied to it.
Final step: set up the internal drive
Now, you need to start up from your external drive in order to repeat the steps on your internal drive.
Pull down the Apple menu and select System Preferences. Click on Startup Disk. In the bottom left corner, click on the padlock icon. Enter your administrator password. Then, click on the external volume that can start up your Mac.
Click on the Restart button.
Your Mac will reboot from the external drive.
Open Disk Utility once you are finished booting. Repeat the partition setup on your internal drive.
Finally, launch Carbon Copy Cloner or SuperDuper. Clone your system partition from your external to your internal drive. Do the same with your data partition.
Everything is done!
Well, almost. At this point, I recommend running a tool such as Diskwarrior or TechTool Pro to optimize your volume structures on both partitions. You just finished moving a lot of data and such optimization will make things zippier.
Also, you will have to set up applications such as iTunes to point to the data partition to store their files. Same thing with Photoshop and its scratch disk.