Not long ago, due to an ongoing issue with my replacement MacBook Pro Retina, I was shipped yet another new model from Apple. I had about a week or so to swap the computers out and return the old one before being charged a fee for the replacement model. This post details the steps you'll need to take in order to complete this process.
1. Backup Everything
Apple's Time Machine software has been included for the last few versions of OS X, and should be very much part of your computer's day to day schedule – whether you're aware of it or not. Particularly with the ability to backup wirelessly to an Apple Time Capsule, or a third party NAS device (just throw
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
into terminal, and the Time Machine system preferences pane will show your network volumes as possible destinations for your backups), there's no reason to not to have already integrated this very much into your workflow, to whatever degree of seamlessness you desire. However, if you for some reason are yet to take the plunge, what you're about to do – move all of your contents from one computer to another – should provide more than enough rationale to overcome whatever inertia is holding you from using this straightforward and sanity-saving backup regimen.
2. De-authorise iTunes
iTunes authorisation, I learnt after my first logic board swap, is very particular. You can't change the internals of the computer without it detecting it as a 'new computer', and thus decrementing the number of computers you'll have available to you to be able to play your iTunes music. You can reset this counter (although this is only permitted once every 12 months, from the first time you choose this option), but this is more pain that it is worth. Just de-authorise all of your iTunes accounts.
The same goes for any other service or programme you might have running on your computer that is particularly sensitive to the machine setup.
3. Copy everything to the new machine
So, you backed up all of your stuff with Time Machine, right? Great! Now you can copy everything across, before decommissioning the old computer. This way, you needn't worry if the new computer has something immediately wrong with it, like an unhealthy hard drive.
When asked during the setup of your new computer, you want to 'restore from disk'. You'll then, by following the prompts, be able to select the name of the old computer's Time Machine backup. The length of the time the restoration takes will very much depend on how much data you have backed up. Don't be surprised if this takes more than an hour or two over ethernet, and much longer over Wi-Fi.
At the end of this process, your machine should be very close to an exact replica of your old machine. For example, the files on your desktop should be the same. Applications might have to download information from the internet again (for example, I lost all of my locally cached Spotify songs), and you might be missing things like printer drivers (I was). Depending on an application, you might have to enter its serial number again. Regardless, this process is the most straightforward and user-friendly way to do get your new machine up and running.
4. Locate InstallESD.dmg
As detailed here, you'll want to create a copy of OS X which you can boot your computer from. The easiest way to do this, by far, is the method described in the link. If you legitimately own a copy of Mountain Lion, but do not have a local copy of InstallESD.dmg, there are likely avenues for you to trawl for a copy in a format you desire.
If you'd rather, you can boot into Recovery Mode (⌘-R at startup), and much should be the same.
5. Only if you use File Vault 2: Decrypt your drive
If you enjoy security for its own sake as much as I do, you'll be utilising File Vault 2. This, in as much a seamless manner as Time Machine for backing up, encrypted the entire contents of your drive. You only need to enter your password once, on bootup, and everything else is taken care for you. You can opt to have apple remember your master key, lest you forget your password, in which case you'll need to provide exact answers (they warn) to some predetermined questions you filled out when setting it up.
Initially bamboozled as to how to decrypt the hard drive for use with Disk Utility while booted on the USB drive, I found that choosing to start up from the boot drive required my password. I entered it, quickly changed out of Startup Disk back into Disk Utility, and was able to proceed to erasing my disk.
6. Erase everything!
The last step is to erase the contents of the old computer that you no longer intend to keep.
Conventional Hard Drives
Depending upon your level or brand of paranoia/insecurity/boredom, you'll want to erase the hard drive's contents to varying degrees. These are chosen by clicking the 'Security Options…' button, and are detailed, as informatively as I could find, here.
This answer on stackexchange details why the usual method of passing over the drive 7 times (à la the DoD 5220.22-M specification, detailed in one of Apple's old knowledgebase articles) isn't necessarily adequate for securely erasing information on an SSD. Regrettably, this approach of using Disk Utility is probably by far the best trade-off between simplicity and security. However, as the answer of stackexchange suggests, full disk encryption is probably a great way around this problem. If you're particularly worried, you should reboot from your main drive, enable File Vault, then skip back to Step 4. You'll have, at least mostly, erased the hard drive, and whatever remains will be encrypted, effectively removing all access to any of your content.
Enjoy your new computer!