How do I partition a HD on imac to run SL 10.6.8 and LION

Scott Malone wrote:

Hello I had to go back a couple of steps before trying to run 2 operating systems.

How do you partition a HD on imac?

Well IF your Mac can run 10.6, like it was upgraded from 10.6 to 10.7 once before, then you can run 10.6 on that machine.

Machines that came with 10.7 in Late 2011 and later cannot.

Another question is if you have enough drive space and it's clear, to run the other operating system in.

So first you have to evauate your drive space, run the BootCamp program in your Utilties folder, it will allow you to create another partiton on the drive as it starts from the bottom free space and works up until it hits Lion data.

If you can create a partition in Bootcamp then do so to the size you need for Snow Leopard.

If you have a problem and it hangs, quit BootCamp and hold command r keys upon boot to get into Recovery and use Disk Utility to Repair the drive. Once that is finished and the Repair is successful, run it again to make sure it's clear. If it has a error or can't Repair the drive, then that's another serious issue. Once the Reair process is complete, then select your MacIntosh HD and Erase > Free Space with Zero option and let it complete, that will likel fix the formatting issue with Bootcamp. Head back and try formatting the Bootcamp partition again.

Once BootCamp has formatted the partition, you need to quit, you don't need it anymore. Open Disk Utility and select the BOOTCAMP partition on the left, change it's name to Snow Leopard, next head to Partiton tab and change the format to OS X Extended Journaled, it will be MSDOS as that's how Bootcamp software format it for Windows.

Now you have a OS X Extended Journated partition on the drive, hold c or option key and boot from the 10.6. installer disk and target the Snow Leopard partiton for installing 10.6 into.

Reboot holding the option key down, this is Startup Manager and you can select 10.6 to boot into, use Software Update fully to get to 10.6.8.

Now you have a dual booting Mac with 10.6 and 10.7

Scott Malone wrote:

Also how does one then use External hard drives as backups to the different Operating systems?

I dont know basic terms like --clone?

time machine?

A clone is a option key bootable exact copy of your OS X boot partiton, it can reside on another partition or external drive.

TimeMachine is just a rotational backup system of your boot drive, it can't be booted to use the computer like before, in case your hard drive dies you can't use it, except to restore only.

Most commonly used backup methods

All about Time Machine