First get Carbon Copy Cloner http://www.bombich.com/
Plug in your external drive and open carbon copy cloner, set your MacBooks hard drive as the source and select your external as the destination. Make sure to check the box to make the destination "bootable". When CCC is done restart your computer holding the option key down to access the boot manager, there select your external as your start up disk. If the imputed starts up on the external drive and everything is there you can then replace your internal drive and reverse the process.
ok, I followed all the suggested steps, and after cloning the original hard drive I booted the computer holding down option, and selected to boot from the external drive. It booted and everything seemed to be there. I shut it down, swapped out the hard drives, and tried to re-boot. With the external hard drive still plugged in, and holding down option, I didn't get a boot menu, just a grey screen with a cursor. I tried it 4-5 times and still got nothing. Any thoughts?
Are you "sure" that when you booted after cloning that the Mac actually started from the external drive? I would pop the original drive back in and restart from that drive. Run Disk Utility to erase and repartition the external. Set it as one partition and make sure to check the GUID box to make it bootable. Select to format as Mac OS Extended Journaled. Then run Carbon Copy Cloner again and clone your internal onto the external. This time instead of using the boot manager go into System Preferences and choose Startup disk and select your external drive. Restart and check to make sure that the external is listed at the top of your available drives in the Finder. If everything is there then swap out again and see if that does it. CCC is supposed to do everything for you to make the drive bootable but maybe it didn't.
I wanted to replace the original hard disk in my mac book pro (13'', mid 2012 / os x 10.8.2) with an ssd drive. I found some guides how to clone the original drive with 3rd party cloning tools, though I used a different approach.
What I needed was (not mentioning screw drivers, etc.):
- the original hard disk
- the new ssd
- an external disk case with sata to usb3 interface, to connect the original hard disk to the mac
Having replaced the hardware (hdd->ssd), I simply booted the mac (now with the empty ssd) with network cable plugged in.
The system started up offering network recovery, though first I used the available disk utility to partition and format the new ssd. Once finished, I selected the option to recover the system from network.
During the recovery my mac had been checked if it is eligible for OS X, and then the recovery continued.
After the system was setup, and running, I run the necessary updates (apple store) and enabled trim for the ssd using Trim Enabler. Finally I connected the original hdd using the sata to usb interface.
OS X recognized the plugged system disk on my "old" hdd and offered to import applications, user profiles and other settings - and I just confirmed to transfer everything. Amazing stuff - it worked like that - even the browser tabs opened showing the same content as used with the "old" hdd.
Apple, this is cool!
(this surprise may be due to the fact by what I experienced with the another OS which uses "professional" or "ultimate" in its name)