I want to create a boot disk of my installed Mavericks OS before I install El Capitan - how?

If you want your current boot disk cloned into an external bootable disk you can use

Carbon Copy Cloner (1 month fullly enabled free demo)

SuperDuper (free for full clone; incremental updates and scheduling is what you would pay for)

Applications -> Utilities -> Disk Utility -> Restore

Assuming you previously downloaded Mavericks, you can download the installer again via the App Store -> Purchases tab. Of course if you saved a copy of the installer from the first time, you do not need to download again. Once you have the "Install OS X Mavericks" app you can use Diskmaker X to create a bootable USB thumb drive, or SD Card, or just a bootable external disk with the installer on it.

<http://liondiskmaker.com>

Hi, read the Create Mountain Install Drive in this MacWorld tutorial. Stash your ThumbDrive for a rainy day.

Here's the link:

http://www.macworld.com/article/1167857/how_to_make_a_bootable_mountain_lion_ins tall_drive.html

Cheers!!

waltg wrote:

Mavericks shows up in my Preferences/Startup Disk... If I install El Capitan, will I get both OS's (Mavericks and El Capitan) as options under Preferences/Startup Disk?? If so, that should relieve my concern...

If you want to create a partition for El Capitan you can have a dual boot system.

But if you just install El Capitan over your Mavericks, then Mavericks will be gone, and you will only have El Capitan.

I have a 27" iMac that came with Mavericks pre-installed, and do not have the install file

You cannot use Diskmaker X for Mavericks, as you cannot get the Mavericks installer any more, and you never downloaded it before Apple removed it from the App Store.

You only option is to create a bootable clone from your current system before installing El Capitan, or to partition your boot disk and make room to install El Capitan as a second bootable system.

Using Carbon Copy Cloner you can selectively exclude files from creating the bootable clone. For example, you could remove all the bulky files from your home directory, which will reduce the size of the clone you make.

I think the bootable clone of your boot disk is the best option.

If you make a full clone, you can always just restore the clone if you decide to abandon El Capitan, plus it is a backup as well. Of course just restoring the clone means any changes you make to your personal documents would be lost.

A more complex revert to Mavericks, would be to backup the El Capitan, then restore the Mavericks clone, then restore personal files you created/modified while running El Capitan from the El Capitan backup.

If you are really concerned about returning to Mavericks, I suggest you actually create a 30 to 50GB partition, install El Capitan on the partition, and see if you like El Capitan before you commit to installing over your Mavericks.