Adding a volume to an already partitioned disk?

Question

Hi everyone,
I am quite savvy when it comes to the Mac; working with different settings through Terminal and using Disk Utility, etc.
As the title says, I am trying to add another partition to my already partitioned Hard Drive, however, I'm having some trouble. I think it will be easiest to outline my current volume setup:
CURRENT: http://cl.ly/3ttK <-- Image
Snow Leopard - 200 GB
Media - 225 GB
Scratch - 75 GB
And what I want to do:
Snow Leopard - 150 GB
Media - 225 GB
Scratch - 50 GB
Design/Development - 75 GB
Using Disk Utility, I went in and changed the sizes of the current volumes to the new sizes.
I clicked on the '+' to add a new Volume to the Disk. When you hover over the '+' button, the description mentions: "Create a partition from unallocated space on the disk". This makes me think that after I had reduced the sizes of the current volumes, clicking this button would create a volume the size of the unused space on the disk.
This isn't the case though. Pressing the '+' adds a new Volume to one of the already created Volumes…
I've thought of changing the Volume Scheme to 4 (only possible while booting from the install discs), however I'm afraid that this will erase all of my data as when I choose this option, all of my current Volume names are no longer there (it's tough to explain this and because I'm booting from the disc at this point, I can't take a screenshot).
Does anyone have any idea how to add another Volume or if changing the Volume Scheme to 4 will do the trick?
Sorry if this has all been confusing, it's tough to get across
Thanks!

Answer 1

AirNJ15 wrote:
This isn't the case though. Pressing the '+' adds a new Volume to one of the already created Volumes…
Actually, that would spit an existing volume.
I've thought of changing the Volume Scheme to 4 (only possible while booting from the install discs), however I'm afraid that this will erase all of my data
*CORRECT !*
Sometimes you can resize partitions, but only by moving the bottom of a partition in the diagram. You cannot move the top.
So it looks like what you want to do is split the Snow Leopard partition, making it 150 GB, and make the remaining 50 GB your Scratch partition.
Then just rename the current Scratch partition to Design/Development.
See [Formatting, Partitioning, Verifying, and Repairing Disks|http://web.me.com/pondini/AppleTips/DU.html] (or use the link in *User Tips* at the top of this forum) for details.
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However . . . this sort of scheme is rarely a good idea. If you're doing it to speed things up, it most likely is actually slowing things down.
Unlike some other operating systems, OSX is designed to work best with everything in the same partition. What you're doing guarantees longer seek times, as the head must travel over all that empty space when it needs to go from something in one partition to something in another.
It also greatly reduces the effectiveness of OSX's "Adaptive Hot File Clustering:" OSX will move things around to get the files it uses the most onto the fastest part of the disk (the top of the diagram), and things that are frequently referenced together in the same part of the drive. As your habits change, it dynamically adjusts to optimize performance.
As it stands, your Scratch partition is on the slowest part of the disk.
Another problem that you don't seem to have (yet) can be having the free space divided up; if the free space in any partition gets too small, your Mac may slow down, and eventually data may be corrupted, apps may crash, and in the extreme your Mac will crash and refuse to restart.