Partitioning A Hard Drive On A Mac 15


Partitioning A Hard Drive On A Mac


I have a lot of hard drives. For example my internal disk on my MacBook Pro is split into to partitions, one for Mac OS X and one for Windows. I have an external backup disk, this is split into two, one for Time Machine and one for a bit more storage. I am soon going to get another disk to use as storage. What I am going to show you in this post is how to partition this disks so you can use them for more than one thing. It useful to have a partition. Its easier to split up files, and makes organising them easier. As well as this you can have more than one disk format on the same disk.

To format a disk, we are going to use Disk Utility. Pick the right tool for the job. You could use another app, but Disk Utility works fine. Disk Utility is found in Applications > Utilities. When the program is opened you will find a screenshot similar to the image below. Select the disk you want to alter. You will have to click on an actual disk, this is the one at the top of a tree of disks. For example in the image below I have selected and external USB disk, below the highlighted area are the partitions. You need to select a disk in a similar way to how is shown in the image.

To partition a disk you need to click on the partition tab. You will be presented with a small rectangle which is a visual representation of how your disk looks. To partition a disk select from the drop down how many partitions you want to make. Alternatively you can use the drag area in the bottom right of the rectangle. Move this up and down to a value you want to set.

The next step is to set a name and format. In the name box type in something useful. It could be your favourite TV character a family member etc. I have called my disk mini-boy, a will soon have another that will be called big-boy. The next step is to set a format. You can choose from Mac OS X Journaled, FAT or Free Space. Choose the Journaled format for the best performance. You can add case-sensitive option but you really don’t need to. Use the FAT format if you want to write from it from Windows. If you want to shrink a disk and not create a partition select free space. Although free space is wasted space in my opinion.

The preultimate step is to check what you have done. Make sure all of your paritions are the correct size, correct format and have a correct name. You can change these later but it takes extra time. Once as you are sure everything is correct press Apply. The changes will come into effect. It will take a bit of time depending on your disk to format everything. Once as the process is done you will have your new partitions.

If you make a mistake you can deselect the drive and re-select it and you can start again. You can do this process as many times as you want, although the more you do it, the more time you use. It is quicker to do it right first time and be done with it. To remove a partition, select the partition and press the minus or delete button. I am unsure at this point whether the deleted partition will be converted into free space or take up by other partitions, I think it would be the former. I haven’t tried this part because I don’t have any partitions I want to delete.

Try the program out, it is simple to use and you can’t really go wrong. But do read the warnings and error messages. Take your time I don’t want a comment saying you wiped your boot disk using this method. If in doubt don’t apply the changes.

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15 Responses to “Partitioning A Hard Drive On A Mac”

  1. 1


    as you mentioned Disk Utility is a quite good tool, I’m looking for something that helps me in a special case (if possible).

    I have two harddisks in my G5 – both 160 GB. At the moment I mirror them, but I also need to partitioning them. This is not possible with Disk Utility. Neither you can partition the combined RAID-Drive, nor you can create identically partitions on both drives and make two RAID-Setups.

    Any Idea what to do?


    Comment By neuwalker on November 8th, at 9:21 am

  2. 2

    That sounds interesting. Can you email me the question, I think it would be easier since I would need to ask you loads of questions.

    Comment By admin on November 8th, at 2:20 pm

  3. 3

    I cant add to that comment I am a reformed pc user. I do have a question though. My normal “user” -me has some corrupt library files so the genius bar people said. The problem was my email kept crashing for no reason and other programs were crashing. Then went to the genius bar and they deleted my library files for mail and still wasn’t functioning correctly. (I have an intel IMac with a windows xp partition). They said to just migrate all but the library files over to a new user. Good luck I had with that…not. I opened my time machine connected to a 1tb time capsule and nothing was there Oh boy I thought this is not good. I played with it all night and then decided to go back to the old user. It’s working ok just seems like things are going a little slow. Should I go back to the new user or any suggestions for the other issue? I really have built up that user and like the way it is moving to a new user plain old sucks. Any suggestions? I read all your tips and guess that you will give me some sort of terminal thing to do…LOL if you do can you walk me through the terminal process I am afraid to mess with that stuff seems like programing and I am certainly a power user but haven’t explored that aspect of computing yet. Hope your holiday is going well that is what they call vacation in Europe right!! LOL thought you might enjoy the humor!! Hope you can help…Please I am begging of you!


    Comment By james KRALICKY on January 4th, at 4:06 am

  4. 4

    @James Kraclicky can you write you comment a bit more clearly, I really don’t understand what you are writing.

    Comment By admin on January 4th, at 12:31 pm

  5. 5

    All this partitioning is done on a drive with data already on it? Is this called a “soft” partition?

    I had always thought that partitioning was done on an empty drive before starting to use it.


    Comment By Bill Hardie on January 5th, at 8:14 pm

  6. 6

    It might be a “soft partition” but it will still move data around and partition the drive as normal.

    Comment By admin on January 5th, at 8:20 pm

  7. 7

    1. I have already partitioned my Mac book pro hard drive to accomodate vmware running windows xp. My problem is the initial partition of 50G was not large enough. I want to increase it to 100G. How c an I use disk utility to do that?

    Comment By ron zelazo on January 7th, at 4:34 pm

  8. 8

    As long as you have space just drag the small handle to decrease the size of the main partition and then increase the size of the second one to make sure everything fits.

    Comment By admin on January 7th, at 4:41 pm

  9. 9

    I partitioned space on my MacBook Pro as well for Fusion, but I deleted it, and need the space back, but I don’t know how to set the partitioned space back to normal. Anyone know how to do this?

    Comment By zilos on January 10th, at 1:23 am

  10. 10

    @zilos just use Disk Utility and grab the partition handle to the full size.

    Comment By admin on January 10th, at 5:38 pm

  11. 11

    Do these partitions work for installing linux? i.e. can you access them without diskutility? I am looking to install Ubuntu along with Mac OS X but people talk about disk partitioning with wary tones.

    Comment By Evan on February 8th, at 12:32 am

  12. 12

    It should be OK, although I haven’t tested it on Linux.

    Comment By admin on February 8th, at 12:47 am

  13. 13

    I recently worked on an iBook with a 40 GB hard drive that failed its SMART test. I replaced the hard drive with a 120 GB drive and cloned the information from the HFS+ partition using gparted from a Ubuntu 9.04 for PowerPC live disk. Unfortunately, gparted (and many other tools I researched and rejected) can only shrink an HFS+ partition, not grow it. In fact, I’m not sure what CAN grow an HFS+ partition at this point. Mac OS’s Disk Utility can resize and format the drive, but neither I nor the original user have the disks to restore the OS, which is why I chose cloning as an option. Also, now that the information is in place, Disk Utility has mostly greyed-out all my options for changing the disk; it says it can’t work on the disk in use, but I also cannot get it to recognize, format, or mount the extra space on the drive. The 40 GB partition is almost completely full, and it was my hope to use the rest of the space on the drive as a data partition. Now I’m not sure how to make it work. I went back and reformatted the 111 GB of free space as a FAT32 partition, but I’m having the same results (or lack thereof).

    Comment By AprilTech on September 1st, at 9:49 pm

  14. 14


    I read on another site that if you are partitioning your hard drive that each partition needs to have its own system files – as a windows user can i ask whether this means that you need to intall osx on each drive or that when you partition and select as journal os the system files will already be installed on each partition – i assume the system files are boot files and trash bins. My intention in to install logic 9 but i want a separate disk(partition) for my samples – what would the best way to do this? Create partition with logic and samples on(journal)? create 2 partitions (1 for logic and its addons and 1 for the samples)? or to throw logic on root drive and create partitian for just samples? will logic be able to run off a partitioned disk? will it be able to access files from another partitoned disk?

    Comment By jason on October 29th, at 1:45 pm

  15. 15

    I have read several sets of instructions and watched a video on how to resize the partitions using disk utility. I just bought this used Mac, and when I try to follow them, I see NO “Partition” option on the bar above the blank space (should be between “Erase” and “Raid.” There is also no text to the right of the empty box.

    Do I have a defective Disk Utility? How can I get a new copy of this application? I did manage to upgrade to OS 10.5.8, but I had to remove stuff from the too-small system volume to do so.

    Comment By Ellen Wedum on January 7th, at 3:29 pm