How to clean install OS X 10.8 Mountain Lion

“With OS X Mountain Lion set to be released later this month, many Mac users are beginning to plan their upgrade to Apple’s latest desktop operating system. When upgrading to Mountain Lion, users will have two options (even though Apple presents only one): an upgrade over either Mac OS X Snow Leopard or Mac OS X Lion, or a clean install,” Brian writes for It’s All Tech.

“Since OS X Mountain Lion will be distributed over the Mac App Store, the easiest method of upgrading is installing it over your current OS. Upgrading over the current OS will keep all of your files, settings, and applications in place,” Brian writes. “The other method (clean installing), however, will erase your entire hard drive and give you a fresh copy of OS X Mountain Lion.”

Read more in the full article here.

[Thanks to MacDailyNews Reader “Fred Mertz” for the heads up.]

22 Comments

    1. Um, it’s a 7-step process, and:

      Step 1 = buy it. same as upgrading.
      Step 3 = Decide if you want to install from a DVD or external hard drive. Not really a step…
      Step 5 = Reboot. Again, not really much of a step.
      Step 7 = Install it. Same as upgrading.

      So, really.. just 3 additional actual steps:

      1. Show Package Contents to locate the .DMG file.
      2. Restore the DMG to a DVD or drive.
      3. Format your drive before installing.

    1. Yes. I wish I had done a clean install of Lion on my mac. I will rectify this when I get my hands on Mountain Lion. 🙂

      1. Eliminates Cruft
      2. Eliminates junk files.
      3. Eliminates any fragmentation that occurs (although OS X is very resilient to fragmentation, it’s not immune)
      4. Clean install = less bugs. Sometimes, there are migration errors that leave you with corrupt libraries.
      5. If you’re installing on multiple macs, having a copy of it means not having to re-download a 5GB file again and again. 🙂
      6. Having a copy means if you’re on the go, and your OS dies, you can use that same flash drive/ DVD to reinstall, even if you don’t have an internet connection.

  1. Right now you can get a mini USB stick from Apple for Lion for somewhere just north of $60.

    I suspect Apple will offer the OS on a USB stick for Mountain Lion, as some people need to update a half dozen Macs in a family.

    The idea of updating a hard drive just never occurs to me. I always get a new hard drive, or if it is an expensive SSD, I clone off the old OS to an external HD, make sure it works, wipe the internal drive and proceed with a “clean install”.

    I’ve never been a fan of in-place upgrading to a new major OS release, because of the occasional glitch and the issues of 3rd party applications and utilities which all need to be checked out for compatibility.

    Multiple bootable clones of your old OS is the only way to know you can survive if the new OS flops for any sort of reason.

    1. I thought that way and almost always updated (not necessarily upgraded) the day Apple made it available.

      Then there was an iTunes update in 2001 with a bug that completely erased hard drives with a space as the first character (http://www.wired.com/science/discoveries/news/2001/11/48149). This was a somewhat common practice among Mac power users, to make drives appear at the top of the open/save dialog windows, and also quickly select the drive after clicking the desktop and pressing the spacebar (obviously Quick Look later killed the latter trick).

      My system was set up that way, and it was pure luck that I wasn’t home that weekend to apply the update. Sure I had backups, but any unplanned system restore as a result of malware or update bug is a serious waste of one’s time.

      Ever since then I’ve always waited at least a few days before applying any updates that ask for an admin password.

    2. I still prefer clean installs, because some developers still don’t know how to make their applications into a package so that i just drag the app to the trash.

      Instead, they litter my User/Library folder with random database files and other utter bullshit….

      Yes, apple has us covered, if you use nothing but apple apps. But because some idiot developers decide not to stick to the proper procedures… we all get f*cked.

  2. There is an alternative to sitting and hoping that your new upgrade won’t be a bad decision because of glitches, (Not that has ever happened with an OSX upgrade):

    Wait until the shakedown cruise has been at least midway or back in port, if you can wait that long.

    I am now giving major upgrades an at least two week hiatus.

    Just a thought.

    As for clean install: most definitely. 8 steps – geez, anal much?

  3. There is no scientific or technical reason to prevent you from doing an upgrade in place. Back up your drive. You do back up your drive, don’t you?

    All this desire for clean installs went out the door with System 9. All the voodoo you hear from “experts” is a bunch of self-aggrandizing chatter.

    1. I agree. I’ve always done in-place upgrades and have never had trouble. I know that some people have had problems. Of course, those are the ones you hear about because obviously if it’s working fine there’s no need to post about it in the support forums.

      That being said, I’m with you… a backup of your drive and an attempt at an in-place upgrade that will more than likely be successful, is all you really need.

    2. Everything is backed up via Time Machine. I too have also done the “upgrade” / overlay option and never had a problem. I was just wondering if there any advantage to a “clean” install – it doesn’t sound like it though.

    3. Generally true. But last year I got a bunch of permissions problems (and even crashes!) with Snow Leopard (originally Leopard) and upgrading to Lion didn’t fix it. But a clean install and careful migration of info, accounts and folders fixed it.

  4. On second thought, having a bootable external Hard Drive or flash drive handy or burning an install disc isn’t too big of a deal.
    Guess I’m still stuck in the mindset of: buy new OS, insert disc, clean install.

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