Restoring from a Time Machine Backup

It’s usually a good idea to wipe off your hard drive and start fresh once every year or so, regardless of what OS you run. In the past it’s been a thing I’ve dreaded mostly due to the huge time commitment involved. My process before was to:

  1. Make sure all important files were backed up (1 hour minimum)
  2. Wipe the hard drive and re-install OS X (1-2 hours)
  3. Reboot and install OS updates (~30 minutes)
  4. Copy all the backed up file back onto the machine (~1 hour)
  5. Install all software needed from installation disks and the web (3-4 hours No thanks to Creative Suite…)

Needless to say, that’s pretty much an all day event. It involved so many steps that were spaced out just enough so that you couldn’t really leave and get anything done. It can also cause a lot of mental stress because you’re always worried with “Did I remember to back up my _____???” In the end, it was worth it though, I got rid of all kinds of junk that had built up and I ended up with a faster machine that’s no longer bogged down.

Enter Time Machine. I began to use this last year and haven’t looked back yet. For those that don’t yet know, Time Machine is Apple’s brilliant and easy backup solutions. You just designate another hard drive for backups, and once an hour it makes a copy of all the files that have changed. Because of this I have pretty much everything I’ve worked on since the beginning of 2008 – and multiples copies of it.

For those curious, I choose to trust my data with a Drobo, which is like RAID for dummies. I’ve got two redundant 1 Terabyte drives – I feel my data is safe.

One of the best new features in OS X was the ability to use that Time Machine backup as a way to restore your computer to a previous state. This is perfect for you if your hard drive crashes, or even if you’re having problems. My initial thought was that if I was having problems, wouldn’t restoring from Time Machine just restore the problems as well? In short, no. Time Machine only backs up your user data, no system files are backed up and noting that can be re-generated will be backed up (things like caches and your spotlight index).

Recently my Macbook Pro was feeling pretty sluggish. Videos didn’t play smoothly, applications took forever to load, and importing and browsing through my photos in iPhoto was painfully slow. It was time for a clean start. Lucky for me, Time Machine removes the majority of the steps I listed above. Basically all that needs to be done now is:

  1. Wipe the drive, install OS X
  2. Restore from Time Machine
  3. Install OS updates

Now this isn’t a quick process, but it’s no longer a thought intensive, worrisome, all day process. So if you’re in a similar situation to mine and you’re already using Time Machine, lets get started! Follow the jump to read more.

time-machine-1 First, you obviously need to make sure you’re using Time Machine. I’ll assume you know how to do this already, but go ahead and make one last backup just to be sure you have the most recent version of all your files. Next, insert your OSX install disk, open the installer, type in your password and your computer should restart and boot from the CD. Go ahead and unplug your Time Machine drive for now, just to be safe.


Select your language, and then before continuing, go up to the Utilities menu and select Disk Utility. In the Disk Utility, select your hard disk on the left (not the hard drive, the actual disk). On the right, click the Erase tab. You could just click the Erase button right here, but when I erase a hard drive I want to be sure I’m actually erasing the data and not just the index. Your choice, but I’d recommend this next step for thoroughness.

time-machine-3Click the Security Options… button, and a pane will slide down with some secure erase options. Select Zero Out Data. If you’re really paranoid, or work for the DOD, select one of the other options. Hit OK, and now ask yourself if you have really got everything you need off the hard drive, there’s no going back after this. Take a deep breath and press Erase.

This part may take a while since it literally goes over your entire hard drive and writes Zeros on every sector. I’ve got a 160GB drive in my Macbook Pro and it took about an hour or two.

time-machine-4Now is a good time to go run some errands, get some lunch, or do the laundry. Once this is done, close out the Disk Utility and continue with the standard OS X installation. I highly recommend a custom installation, be sure to not install languages you don’t speak, and printer drivers for printers you don’t own and will never own. Now is a great time to get to that ironing you’ve been meaning to do.

After OS X finishes installing you will be presented with the migration assistant. Plug in your Time Machine drive, and select to transfer your data from the Time Machine drive. Select which drive to transfer from, and then select what dat you want transferred. Usually you’d want to restore all your data, so I’d say just go with that. This part may take a while to calculate how much will be restored, so just wait a few minutes and then continue when it lets you.

time-machine-6If you haven’t caught on on LOST, now is a great time. I had about a years worth of backups, and it took around 2 hours to restore completely, just enough time to re-watch that season 5 premiere! Once that finishes, just enter in your information and that should do it. You now have a fresh install of OS X, but will all your data just as before!

First things first though, head up to the apple menu and select Software Update to make sure you’ve got all the latest updates. Install them, restart, and check again. Some updates require others first, so you may get a new set of things to update after the first round of updates. That’s it, you’re done!

Something to keep in mind though is that Time Machine does not back up anything that your Mac can re-build itself. This includes things like your Spotlight index, caches, and your Mail index. The first time you open Mail, you will probably see something like the image below. No big deal, but it’s just something to be aware of. The same thing goes for opening programs for the first time, it’s going to ask you if you’re sure you want to do that since it’s the “first” time it’s been opened on this fresh system.

Hope that was helpful to someone. I tried this process without knowing for sure how it would work, and it turned out to be exactly how I imagined it would be – easy.

(EDIT 1/31/09) – After doing this restore and using my computer for a few days I noticed that Time Machine was no longer doing regular backups! Turns out that for some reason Time Machine is set to Off be default after an install of OS X. Be sure to go into the preferences and turn this back on to continue backing up your data!

10 replies

  1. dtmmedia says:

    Ha, so I see you’ve been “drobotized.” I’ve been wanting one but currently lack the $$$ necessary. Great post though, I may have to give this a shot. It’s probably been about a year or so since I last reinstalled OS X (and that was before I was using Time Machine so I had to do it the old fashioned way, as you described in the post). I’ll probably wait until I start to see some issues that motivate me to go through with it, but this sounds like it will make the whole process a lot simpler.

    • Chris Barr says:

      Yes the Drobo is awesome and easy…but expensive. I had my 500GB LaCie drive completely fail on me and I lost some (but not all) of my data. That’s when I said “no more” and coughed up the cash for a Drobo.

      Yes, try this process, afterwords it’s exactly the same computer as before, you get right back into the flow of working. Easy.

  2. Derek says:

    Glad to see that this works so well with time machine. I need to do it on my macbook, it’s been a couple years.

  3. Shem says:

    Hey, thank for the info. What app is allows for the red and green data speed on your sidebar to be shown?

  4. Shem says:

    Ahh, thanks again for that. Its working swell on my sidebar now.

  5. Sydney says:

    Thanks for this very useful and simple instruction!

  6. Keith Morrison says:

    Great instructions puts things in simple terms.

    If i wipe and install, then use a time machine back up, will unwanted apps and apps resources be reinstated?

    • Chris Barr says:


      Yes, if you restore from a backup, it will restore everything that is backed up.

      I believe you get some basic options on what to restore, ie. applications, music, photos, etc.

  7. michael says:

    i can’t thank you enough.. i just bought the drobo drive
    for this purpose.. my macbook is so slow that opening
    safari can take a generation.. i can’t do the clean until my snow leopard disk arrives but in the meantime i’ve
    gotten everything backed up via time machine.. i didn’t
    get it until i read your post as to how it was all going to pan out so i salute you for your generous effort..
    kindly and appreciably


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