A guide to dual/multi boot (No BootCamp)

I am making this because of all the trouble I went through before I successfully multibooted my mac. I figured out the process is SOO much easier than described in all the walkthroughs I had read. I am assuming if you are reading this, you have some sense of what you're doing. WARNING: This could seriously mess your system up if you delete, format, or install on the wrong partition. So, here is my multibooting walkthrough.

First off, I am running Snow Leopard 10.6.8 on a Macbook Pro 7.1, but I'm pretty sure the process is not much different in other Mac OS versions. I was multibooting with Windows 7 and Ubuntu, but had another Linux OS when I was trying to figure this out. I currently am not multibooting, becuase I picked up a few desktops to run Windows and Linux on. Lets begin:

1. FORGET ABOUT BOOT CAMP ENTIRELY. Boot Camp allows you to install only one Microsoft OS, and offers no support for a Linux based OS. It really isn't that hard to do this without Boot Camp, and Boot Camp can hinder the process. (Unless you are only interested in installing one Windows OS, then Boot Camp is good. It is harder, however, to use Boot Camp and decide later on to multiboot.)
2. Open Disk Utility. It can be found in the Utilities folder, which is in Applications.

1. Locate your hard drive, and highlight it. It should be the top most disk in the box on the left.
2. Find the "Partition" tab, and click it. Your hard drive SHOULD be the only disk with a "Partition" tab.
3. Press the "+" button to add a partition. (Note: If you are multibooting, it's probably easier to do this process for each OS one at a time. It is easier to keep track of the partitions when there is only one blank one. Also, creating distinct sizes for each partition will help you differentiate the partitions, when you get to the installing step. In example, 27GB & 23GB is easier to tell apart than two 25GB partitions.)

1. Select the desired partition size, by either typing it in the "Size" field, or dragging the slider on the blue and white rectangle. (Note: You cannot slide into the blue area, because this is space currently being used. If you somehow do, you WILL mess something up.) You can name it if you'd like, but I dont think you will see the name again, the new OS will rename the partition.
2. Once you have your partition the desired size, click "Apply". A progress bar will appear, let it finish completely before moving on.

Now put your OS disk in, restart your computer, and boot from the disk. To boot from a disk with the Macbook Pro, hold down the "c" key while it's starting up.

(Skip to 9 if you have a bootable disk already.)

Note: If you are like me, (or using a free Linux) you probably have the OS disk somewhere on your computer in a ".iso" (or ".dmg") file. (be sure you do not break copyright laws obtaining the iso). If you are having trouble making the iso file into a bootable disk, this can be done in Disk Utility also.

1. Drag the UNMOUNTED iso into the list of disks, on the left side of the Disk Utility window (where you found your hard drive in step 3). DO NOT MOUNT OR OPEN THE DISK IMAGE.
2. Highlight the UNMOUNTED iso, and click burn.
3. Another progress bar will pop up, again let it finish completely.

1. After you boot up from the disk, it's time to dictate where/how to install the OS (sorry, I have no screenshots). BE CAREFUL WHICH OPTIOINS YOU CHOOSE ON THIS STEP. YOU CAN ALWAYS DO A HARD REBOOT IF YOU AREN'T SURE WHICH SELECTION TO MAKE. REBOOT IS LESS RISKY THAN MESSING UP THE WRONG PARTITION. There will be an option to erese everything and install the new OS, don't do that. There should be another option to configure the partitions manually, do that. Also, be careful which partition you choose (this is where the specific sizes come in handy, and that 27GB partition will be easy to find). You want to be sure not to install the OS over your original partition, or any of the (very small) system partitioins.
   1. Find the desired partition in the manual configuration section, and click to edit it. This will probably open a seperate, partition editing window.
   2. There will be a dropdown list, whose default setting will say something like, "Do nothing with this partition," Change that. I always pick the top most option, but any will do as long as a box, allowing you to choose what folder to mount the file system to, appears. Also, your selection should allow you to check a box to format the partition, which is probably in the first window, the one where you selected what partition to edit.
   3. Still in that second window, change the folder it mounts to, to " / " (just the slash) and click "Apply".
   4. Then check the box, "Format Partition" before clicking continue. WARNING: If you format the wrong partition, it's game over.
   5. It will ask about a "Swap Space Partition", but I have never made one. I just continue without it.
2. After step 9, the rest should be a normal install. Select the preferances you favor.

If I made that clear enough, your system should now be partitioned and multibooted. Just repeat the process as many times as you need.

To switch between partitions, hold down the "option" key during startup, and a menu with the available partitions will be shown. I don't know if there is an option to always show the partition menu at startup, or not. If you do want to see a menu every time, rEFIt is the program I was using. You can download it here. Mount this disk image, then open the file "rEFIt.mpkg" inside it. Follow the installation menu (I'm pretty sure you need to be logged into an admin account to install rEFIt).

You can remove a partition entirely in Disk Utility, by clicking the " - " (next to the "+" from step 5), while highlighting the partition you want to delete inside the blue and white rectangle. Drag the slider as you please to fill the space leftover from the removal, then click apply (if you dont do this you will have unusable hard drive space the size of the deleted partition. if you forget you can resize later, no big deal). There are instructions on removing rEFIt on the rEFIt website.

It sounds harder typed out than it really is. I spent some time on this, so I really hope it helps at least one person.