Today we have a guest post by Chris Wanja. He wanted to do a post on creating different bootable disks which you can use on an external hard drive. For example a Leopard Boot and a Snow Leopard Boot. This means you have two different operating systems which you can use and allows you to try things out in different operating systems. This method is slightly different to the bootable backups I did a couple of days ago. The method is quite complicated so you have to follow the instructions quite carefully. I recommend people who know what they are doing attempt this tutorial as you can easily lose all of your data. If you have any questions please leave a comment below or Twitter.
“In the post we cover how to create bootable, clean operating systems as well as bootable installers. Some plus sides to creating a bootable drive is the ability to defragment your own hard-drive. Defragging simply moves broken up sectors on your hard-drive back inline so they are side-by-side. This increases the response of your operating system when you request a file. To read more on defragmentation, check out this Wikipedia article. On a Windows machine, they include the ability to defragment right from inside the operating system. On the Mac, you have to purchase a software CD such as Drive Genius and then boot into that CD. With a bootable operating system, you can load via that and defragment right from there. It is a lot faster over FireWire or USB than a bootable CD. Creating a bootable operating system installer makes things so much faster than installing off a retail copy or grey discs included with your Mac. The latter part of this post will show you how to great a bootable operating system while this next section will show you how to create an installer partition.
Go ahead and plug in and turn on your hard-drive. Insert the retail copy of Tiger, Leopard, Snow Leopard or which OS you would like. Let it mount on your desktop. As soon as it mounts, fire up Disk Utility found in your ~/Applications/Utilities folder. In Disk Utility you are welcomed with a screen that has your local hard-drive and your optical drive. For users on 10.3 or lower, Disk Utility will not mount your optical drive. At this point, you will see your internal hard-drive, CD drive and any external hard-drives connected. Choose the main hard-drive (the brand name) on the left hand side. Across the center, choose the partition tab and create two (2) partitions for every operating system you would like to install; one for the installer and one for the clean boot. Use all of the sizes below to make sure you have enough space partitioned:
- Snow Leopard:
- Install: 12GB
- Operating System: 15GB
- Leopard
- Install: 15GB
- Operating System: 20GB
The picture below shows five (5) different partitions. On a small 500GB disk I have my TimeMachine, 10.5.6 Installer, 10.5.6+ OS, 10.6 Installer and the 10.6 OS. Choose the partition you want to send the installer too. Notice the buttons across the middle box change when you select a specific partition. Go to the “Restore” button. Feel free to read the text at the top, but our focus will be on the input spaces in the lower half of the box. The first box is for your source (the install CD) and below that is for the hard-drive partition you want it to install to.
Next up is installing a clean operating system on an empty partitioned hard-drive. We just created an faster way to install the operating system, so lets go ahead and use that. Make sure there is an empty partition waiting for your OS install. If not, go back into Disk Utility and create a partition (as described above). Shut down your computer (or restart) and as soon as you see the grey screen hold down the option/alt key – ⌥. This should bring you to the screen show you all bootable drives. You will see your internal drive (Macintosh HD or what you have it named as) and then you will see the partition with the installer you just created. There should be only two drives, so you should not be to confused, try doing it with five different bootable OS and installers. Choose the installer partition and you will be booted into it just as if you were doing it off the CD. Follow the prompts just like you would to re-install. The only difference is when you come to the screen that allows you choose the hard-drive, make sure you choose that empty partition. DO NOT CHOOSE YOUR INTERNAL HARD-DRIVE – it should have a yellow triangle on it. Consider that a big red stop sign and choose the other. Finish the installer and it will reboot. When it reboots it is scripted to go to that operating system it just installed. So make sure you hold down the option / alt key to choose your internal hard-drive (unless you want to go into the new operating system you just created).
You have successfully created a FireWire or USB installer and bootable operating system. There is a couple of different ways of access these new jewels of yours.
- Easiest: restarting and holding down the option / alt key. Then choose the partition you want to access.
- Pain in the neck: Open System Preferences, go to Startup Disk, unlock, and choose the external drive. The reason I call this the pain in the neck method is for two reasons:
- On turn on, the OS will constantly look for that external partition. When it doesn’t find it (because it is not always plugged in) it will default to your internal hard-drive. This adds about ten seconds to the boot time.
- If the drive is plugged in, it will always default to that (until you change it). Making it a pain if you forget”