Home Apple How to Perform a Clean Install of OS X Yosemite

How to Perform a Clean Install of OS X Yosemite

OS X Yosemite is officially out and ready for the public. It’s the latest OS X version from Apple and it comes with a heap of new features, including an all new look and Handoff (which lets you go back and forth on your iPhone or iPad with certain tasks).

OS X Yosemite is available now in the Mac App Store for free.

While most users will be fine with the easy upgrade process that OS X has, some users prefer to start from scratch with a clean OS install whenever they’re upgrading to an all-new version. A fresh and clean install means your computer’s hard drive is completely erased and OS X Yosemite is installed to factory settings. This means that no apps are installed and no files are stored — just the default apps and files that come with OS X Yosemite.

Personally, I always do a clean install. There are just too many problems that could happen when simply just upgrading, and I have so many files that they could get disorganized and cause unnecessary slowdowns after I upgrade. Essentially, when you do a simple upgrade, the new OS gets installed, and then the installer picks up all the old files and dumps it on top of the newly installed OS, which could easily cause problems.

OS-X-Yosemite

With that said, here’s how you can install a fresh copy of OS X Yosemite and start with a clean slate.

Be warned, though: Performing a clean install of OS X requires you to make a bootable install drive using a USB flash drive. You’ll be moving a lot of files around and dealing with Terminal. If this isn’t something you’re comfortable doing yourself, we’d suggest simply upgrading, or grabbing a friend who can help you perform a clean install.

Preparation

First, you’ll want to make sure that OS X Yosemite is supported by your Mac. Some Macs as far back as 2007 support OS X Yosemite, but for a full list of supported Mac models, check out this list.

You’ll also want to back up everything before you begin the clean install. You can either use Time Machine to easily backup all of your files to an external hard drive, or you can manually pick and choose files that you want to keep, and then transfer them to an external hard drive or USB flash drive.

Next, download OS X Yosemite from the Mac App Store. It’ll download and save to the Applications folder automatically. Furthermore, after it’s finished downloading, it may automatically begin the install process. If this happens, just quickly cancel it.

Making the Bootable USB Drive

In order to install a clean and fresh copy of OS X Yosemite, you have to create a bootable install drive using either a DVD, USB flash drive or an external hard drive. For this tutorial, we’ll be using a USB flash drive, since not everyone has an optical drive on their Mac, and you most likely have a USB flash drive anyway. Just make sure it’s at least 8GB in size.

IMG_0253

  1. Plug in your USB drive and open Disk Utility.
  2. Select the USB drive in the sidebar and click on the Erase tab.
  3. Select Mac OS Extended (Journaled) in the Format box and name it Untitled (It should already be named that).
  4. Click Erase and wait for the format to finish.
  5. When it’s done, close Disk Utility and open Terminal. Type in the following command and press Enter:

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction

This command will officially make the USB boot drive and it’ll take about 20 minutes to complete, give or take. While it’s doing its thing, don’t mess with Terminal or eject the flash drive. Once done, it’ll say Copy complete. Done.

Installing OS X Yosemite

Now that you have a bootable USB stick with OS X Yosemite on it, it’s time to install it. With the USB drive plugged in, reboot your Mac and hold down the Option/Alt key. This will bring up a menu where you’ll select an install drive. Choose the USB drive that you just made (usually called OS X Base System in this case and will be colored orange). Click on the arrow pointing upwards below the drive icon to get started.

IMG_0247

Now, before you install OS X Yosemite, you’ll want to erase and reformat your hard drive, so at the Install OS X screen, go up to the menu bar at the top and click on Utilities > Disk Utility.

IMG_0250

From there, follow these steps:

  • Click on your main hard drive in the left-hand sidebar.
  • Click on the Erase tab and make sure Mac OS Extended (Journaled) is selected in the Format field.
  • Give the hard drive a name. If you want to stick with the Mac naming convention, go with Macintosh HD.
  • Click Erase in the lower-right corner to begin the wiping process.

IMG_0252

  • After that’s done, close out of Disk Utility, where you’ll be brought back to the Install OS X screen.
  • Click Continue to begin the OS X Yosemite installation process and follow the steps provided.
  • Enjoy OS X Yosemite!

This is a fairly complicated method for creating a bootable install drive, but we’re guessing that once OS X Yosemite has been out for a few months, there might be some third-party tools released that will make the bootable disk creation process a bit easier, similar to that of OS X Mountain Lion tools that easily created a USB install drive for you. For now, though, this seems to be the quickest way that works.

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29 Comments

  1. John Johnsen

    10/16/2014 at 9:40 pm

    A great tutorial, simple and to the point – And it worked without any problems.
    Just remember to move the arrow to under the yellow hard disk install Yosemite when installing.

    Thank you.

    Reply

    • Mohammed Naseer

      10/18/2014 at 9:09 am

      Hi – I would advise NOT go down the “bootable install drive using a USB flash drive” route simply because I have run into problems later down the road after the install had completed with certain apps not functioning properly but after doing it the official apple way ( listed below ) my apps worked fine.

      1, Download and install the OS X as usual from Apple’s ‘App Store’ ( i.e upgrade it assuming your source OS is 10.7 or newer ).

      2. Backup your essential files

      3. OS X: How to erase and install ( using Recovery System, available on all OS X’s since 10.7 LION ).

      Important: Before you erase and reinstall, back up your essential files. If you’re installing on a notebook computer, make sure your power adapter is connected and plugged in.

      Use these steps if you need to erase a disk before installing OS X:

      A. Before you begin, you need to be connected to the Internet.

      B. Choose Apple menu > Restart, and then hold down the Command (⌘) and R keys while the computer restarts.

      C. Select “Disk Utility,” and then click Continue.

      D. Select your startup disk from the list on the left, and then click the Erase tab.

      E. From the Format pop-up menu, select Mac OS Extended (Journaled), type a name for your disk, and then click Erase.

      F. After the disk has been erased, choose Disk Utility > Quit Disk Utility.

      G. If you’re not connected to the Internet, choose a network from the Wi-Fi menu in the right corner of the menu bar (in the top-right corner of the screen).

      H. Select Reinstall Mac OS X, click Continue, and then follow the instructions.

      Reply

      • Jahangir Amin

        02/26/2015 at 2:47 am

        Hello Naseer,

        Due to regular power outages, i am not able to upgrade to OS X yosemite. my download doesnot resume after even downloading 3 GB. Could you please help me in any way. Is there any link where i could find the .apk file for download and then install it offline

        Thanks

        Reply

  2. Ken

    10/16/2014 at 11:03 pm

    Great tut. To keep it simple, while erasing your flash drive just leave the default name as untitled. Then you can copy and paste the above terminal command.

    Reply

  3. RF9

    10/17/2014 at 12:23 am

    I always wondered why Apple doesn’t make this easy. Would it be so hard to include making a bootable USB stick an option when launching the installer?

    Reply

  4. Sebastian

    10/17/2014 at 6:06 am

    Great Tutorial!! . . . thanks a lot

    Reply

  5. Neil

    10/17/2014 at 6:10 am

    Thanks!

    Reply

  6. Torontonian

    10/17/2014 at 6:52 am

    Nice tutorial!

    However, I have a quick question. I did not try to install Yosemite yet but I’m wondering if that terminal part is actually necessary.

    I created a bootable USB stick with Mavericks and the last tutorial I had read mentioned the same terminal trick. However, I never used the terminal and managed to create my bootable USB stick without any issues.

    Maybe the process has changed a bit with Yosemite and maybe it’s compulsory now. That’s why I’m wondering. I just did a clean install of Mavericks a few days ago (forgot to check on the release date of Yosemite… DOH).

    Here’s the process I used with Mavericks, if someone wants to try it with Yosemite and give us their feedback, that would be great. That would give us 2 working options… or we would have eliminated the non working one :)

    1. connect your USB stick (I used a 8gb flash drive)
    2. Open disk utility and format the stick as follows: Mac OS X extended (journaled)
    3. Open the Mavericks (replace Mavericks with Yosemite) disk image
    4. Drag and drop the installer into Disk Utility
    5. select your newly formatted stick and select “restore”
    6. in the source field, select the Mavericks/Yosemite installer (the one your dragged into disk utility)
    7. in the destination field, select your usb drive
    8. Erase the destination (the stick is already formatted so no need to be worried about that step)
    9. Click restore and voila.
    10. restart your mac while holding down the option key and select the USB stick as the main booting device

    That’s how I got my Mavericks bootable USB drive. No terminal involved. It may be less scary for some users. However, as stated earlier, I DID NOT TRY WITH YOSEMITE. It may not work anymore. And as I just re-installed Mavericks, I’m not going to re-install Yosemite right away.

    Reply

  7. Michele

    10/17/2014 at 6:56 am

    Does it work the same if I have upgraded, something got messed up and I reinstall from the recovery HD partition after erasing the disk?
    Thank you

    Reply

    • Dan

      10/17/2014 at 3:14 pm

      Yes, this is another way to accomplish the same task. Once you’ve upgraded, you can wipe your disk and reinstall from the recovery menu. Note that it will download the installation files from the Internet, so a connection is required, whereas this article allows you to do it offline.

      Just hold Command+R while powering on your Mac until you see the Apple logo. Then use the Disk Utility to erase the disk, followed by choosing the Reinstall option.

      Reply

      • Mohammed Naseer

        10/18/2014 at 9:03 am

        Hi – I would advise NOT go down the “bootable install drive using a USB flash drive” route simply because I have run into problems later down the road after the install had completed with certain apps not functioning properly but after doing it the official apple way ( listed below ) my apps worked fine.

        1, Download and install the OS X as usual from Apple’s ‘App Store’ ( i.e upgrade it assuming your source OS is 10.7 or newer ).

        2. Backup your essential files

        3. OS X: How to erase and install ( from Recovery System ).

        Important: Before you erase and reinstall, back up your essential files. If you’re installing on a notebook computer, make sure your power adapter is connected and plugged in.

        Use these steps if you need to erase a disk before installing OS X:

        A. Before you begin, you need to be connected to the Internet.

        B. Choose Apple menu > Restart, and then hold down the Command (⌘) and R keys while the computer restarts.

        C. Select “Disk Utility,” and then click Continue.

        D. Select your startup disk from the list on the left, and then click the Erase tab.

        E. From the Format pop-up menu, select Mac OS Extended (Journaled), type a name for your disk, and then click Erase.

        F. After the disk has been erased, choose Disk Utility > Quit Disk Utility.

        G. If you’re not connected to the Internet, choose a network from the Wi-Fi menu in the right corner of the menu bar (in the top-right corner of the screen).

        H. Select Reinstall Mac OS X, click Continue, and then follow the instructions.

        Reply

  8. Cark

    10/17/2014 at 9:55 am

    I had done the bootable flash drive install with Marvericks a while ago, using the Terminal way. After i moved everything back from my time machine back up, i found out that Find My Mac was not working. There seemed to be something missing with this Terminal option. I wonder if this will happen also with this Yosemite bootable flash drive option using Terminal….

    Reply

  9. Pierre

    10/17/2014 at 5:48 pm

    I just found out that if you copy the installer file on any pendrive it shows up as bootable install volume after a restart. So.. no need really to make a bootable drive… any pendrive with the install will do…

    Reply

  10. Bob

    10/17/2014 at 8:22 pm

    I got to the install step father erasing the drive. However, after Yosemite loads, it says that the sub disk is corrupt? I don’t see how that happened. Is there a workaround?

    Reply

  11. Andreas

    10/18/2014 at 1:26 am

    It’s been well over 40 minutes since i started in terminal. This is what it says:

    Erasing Disk: 0%… 10%… 20%… 30%…100%…
    Copying installer files to disk…

    There seems to be no activity at all. Is something wrong?

    Reply

  12. Alex

    10/31/2014 at 10:35 am

    Hi,

    I’ve just red your tutorial and a doubt came around: will your tutorial keep keep the Recovery partition untouched, or will be erase at all? If this will happen, I suggest to initialize the hard drive running Disk Utility from the Recovery partition – the Mac should be forced to keep that partition untouched. Then, you can reboot the Mac with the USB drive and follow the onscreen directions.

    What do you think about it?

    Reply

  13. M.C.

    11/01/2014 at 6:10 pm

    I don’t know how or why the idea of creating a “bootable” version of a new release of OS X by using a Flash drive, getting involved with Terminal, etc., became such a big deal in recent years, but it’s completely unnecessary and a waste of time. I always do clean installs for the same reasons that the author lists. But why make it more complicated? I’ll just add a few more details to the comment posted above by Mohammed Naseer.

    Assuming you have solid Time Machine backups (this is arguably the most important thing to have) on an external hard drive that has been connected to your Mac, all you have to do is go the Mac App Store and upgrade Yosemite from the Mac App Store, which will install it on top of Mavericks. This is, indeed, NOT what you want, but it’s only a temporary step.

    Once Yosemite is installed on top of Mavericks, shut down your Mac. Then reboot it while pressing Command+R on your keyboard right after you hear the booming launch sound. This will take you to OS X utilities. Click on Disk Utilities. Then click on your your Macintosh HD (the one that is indented and second on the list in the Disk Utilities side bar) and “Erase” it. (NB: Don’t erase your external hard drive that will be listed below the Mac HD, or you are screwed.)

    This will wipe your internal hard drive completely and get rid of all of the crap that has built up in your Mac over the years–cookies, caches, corrupted .plists, evil implants from Google and Facebook, and other junk that bogs down your computer and can cause conflicts between Mavericks and Yosemite. You don’t want to restore that stuff to your newly cleaned hard drive.

    But, fear not: if you have a good Time Machine backup, all will be well (see more below). This method also, as an aside, allows you to avoid using Migration Assistant, which will bring back all of the crap noted above that you just erased.

    When your hard dive is erased (which takes about 30 seconds), your screen will return to OS X Utilities. At that point, click on “Install OS X” (or whatever the verbiage is; you’ll see it). Don’t click on the option to restore from a Time Machine backup because, again, that will just bring back the junk that we are trying to keep off of the clean hard drive.

    This step will download Yosemite, and then you just follow the instructions that OS X gives you for the path to the Promised Land of a “clean install.” Once that’s done, your computer will restart on its own, and you’ll have a new version of Yosemite (Mavericks and its legacies will be gone) and the basic, native Apple applications that come with OS X on your Mac. It’s like having a brand new Mac computer.

    At that point, you need to take the key step: Go to “Enter Time Machine” in your menu bar. Doing this one step at a time, click on the Documents, Pictures, Movies, and Music folders in the Finder window of your most recent backup and “Restore” each of them. These precious items in those Finder folders will magically reappear on your computer’s internal hard drive in their proper locations. It make take a little time, depending on how much stuff you have in those folders, but it’s worth the wait.

    Once those items are restored to your hard drive, make a trip to the Mac App Store and click on “Purchases.” Download only those applications that you really use and not those that have just been sitting on your hard drive, unused and taking up (and wasting) space. As for third-party apps that you’ve purchased, but which are not in the Mac App Store, you’ll have to go to their websites and re-download them and enter your licensing information. Not a big deal.

    FINALLY, when all of these steps are taken, you must go back to our friend, Time Machine, and do a full backup of your entire internal hard drive on your external hard drive. I recommend that, before doing a full backup, click on the “Options’ button in Time Machine and exclude some things that you don’t need to backup (e.g., caches in your User Library). A Google search will tell you what is safe to exclude from your Time Machine backup.

    After the full backup to your external hard drive, you will be the proud parent of a “new” Mac with a clean install of Yosemite and all of your most important stuff restored to your hard drive. Your life will be much happier.

    Yosemite is amazing, and it’s much better without the garbage that naturally attaches to your hard drive over time. And you don’t need to screw around with a “bootable” version on some Flash drive. There is no value in that method.

    Reply

  14. grwm

    11/03/2014 at 4:05 am

    Thanks! Very good instructions.

    Reply

  15. Benjamin Castro

    11/06/2014 at 4:33 pm

    Great instructions, work like a charm. Thanks

    Reply

  16. trent reed

    11/08/2014 at 9:48 pm

    worked perfect for me the way the original author intended. thanks for this!

    Reply

  17. Art Cardenas

    12/06/2014 at 8:55 am

    Solution to error -69888: label your USB drive YosemiteUSB, otherwise you might get an error like

    Erasing Disk: 0%… 10%…
    Error erasing disk error number (-69888, 0)
    A error occurred erasing the disk.

    Reply

  18. Allana

    12/12/2014 at 12:00 am

    Thank you so much. I followed your instructions to the letter and I have an old imac who is a proud problem-free working machine; she is a happy computer; I am a happy user.

    Reply

  19. Ron

    12/17/2014 at 8:32 am

    It was slow and tedious, but your instructions were spot on. Thanks

    Reply

  20. Aden

    01/03/2015 at 1:43 am

    My terminal has been stuck at the following for over 2 hrs:

    Erasing Disk: 0%… 10%… 20%… 30%…100%…
    Copying installer files to disk…

    Is this suppose to happen and should I exit terminal and start over?

    Reply

    • M.C.

      01/03/2015 at 10:08 am

      Aden–No, that’s not supposed to happen. Since you are in Terminal, serious problems (e.g., loss of your data, among others) could happen to your Mac if you do something wrong at this point (hence, my advice above to avoid going down that path with Terminal for a clean install of Yosemite). If you are still having problems, I urge you to call AppleCare and explain to a technical adviser what’s happening. Since your issue involves installing Yosemite, the call will be free. (800-275-2273). I wouldn’t do anything with your computer until you speak to AppleCare.

      Reply

  21. Harrison

    01/24/2015 at 2:29 pm

    HELP! I have a bootable usb stick with the os x mavericks installer on it but whenever I start up the computer holding the alt key it is never an option to select my usb stick just the hard drive. I don’t know what is going on and this is really quite frustrating so some feedback or help would be great.

    Reply

    • M.C.

      01/25/2015 at 12:18 pm

      Harrison,

      I suggest you bail out on the USB/bootable drive approach for conducting a clean install of Yosemite before you lose any data on your computer. It’s too complicated and adds no value to the process to have the installer on a USB. It’s not worth the hassle. See my recommended approach in the comment above on 11/01/14 and what to do if things are really screwed up in the comment on 1/03/2015.

      Reply

  22. J.E.F.

    08/04/2015 at 8:14 am

    Wonderful help. Thanks!

    Reply

  23. Brian

    03/26/2016 at 5:43 pm

    IGNORE the person who posted twice saying “I would NOT recommend booting from a flash drive …” – that’s just CRAZY TALK. Everyone under the sun except a few IT system admins with a network installer does it this way. It is the safest, cleanest way and does not require an internet connection for this standalone install. Nonsense like Nasser posted needs to be treated with utter contempt. Great tutorial, will keep newbies out of trouble.

    Reply

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