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Special Note for Adding an SSD to a 2012 Mac mini.

Tuesday, November 20th, 2012 | Author:

The “Fusion Drive” option for the 2012 Mac minis can cause some severe data loss if you’re not careful. It’s a bit of a “perfect storm,” but it’s worth noting if you’re adding an SSD as a second drive in your Mac mini.

This particular instance affects you only if:

  • You are upgrading a 2012 Mac mini.
  • That 2012 Mac mini shipped with Mac OS X 10.8.2
  • You are adding an SSD to this Mac mini as a second drive, alongside the existing Hard Drive using an OWC Data Doubler Kit.

If your installation involves all three factors, then you need to pay attention, as your installation will be affected. If one or more of these factors are not involved, then you don’t have to worry, you can proceed as normal.

If you are one of the affected Mac mini owners, then installing an SSD is a little different. The preferred method is the “Internet Restore” method. Perform the following steps in order to format your SSD and transfer your OS and data from your original drive.

  1. Make sure your data is backed up, just to be safe.
  2. Install your SSD in your Mac mini, following the instructions.
  3. Restart your computer and boot to the internal hard drive like normal.
  4. You will likely get a dialog box stating that a drive is “unreadable.” Click the “Initialize” button to open Disk Utility. If you don’t get this warning, you can find Disk Utility at Applications/Utilities/Disk Utility.app
  5. Select the SSD from the list on the left side of the Disk Utility window and Click on the Partition tab.
  6. Select “1 partition” for the Volume Scheme, set the format to “Mac OS Extended (Journaled)” and give the drive a name. You can then click the “Apply” button to format the drive.
  7. Once the drive is formatted and shows in the Finder, you can then shut down.
  8. Make sure you’re connected to a network. While it’s preferable that you connect via Ethernet, you can connect via AirPort; it will just be slower.
  9. Restart to the OS X Recovery Partition by holding down Command-R until you get the Recovery Partition’s main window. It is very important to note that you should not use the version of Disk Utility in the Recovery Partition; it will see the two separate drives as a “damaged” Fusion drive and try to repair it; allowing it to do so will destroy your data.
  10. Select the option to “Reinstall OS X” choosing the SSD to install the OS on. If you’re connecting via AirPort, you may be prompted to connect to your wireless network.
  11. Follow the prompts to install.The actual downloading and installation process may take a while.
  12. After the OS is installed, follow the prompts to set up your computer. When asked, choose the option to import your data from another drive and select your original drive as the source.
  13. Once the migration is complete, your computer should boot to your SSD.
  14. You can use the Disk Utility like you did before and format your original hard drive as desired.
  15. You will now be able to use your Mac mini normally.

While the above method is the preferred way to do this, if you do not have an Internet connection, you won’t be able to reinstall your OS this way. In this instance, you will need to use the “External” method.

  1. Install your SSD in an external enclosure (USB or FireWire) and connect it to your Mac mini.
  2. Boot to your Hard Drive.
  3. You will likely get a dialog box stating that a drive is “unreadable.” Click the “Initialize” button to open Disk Utility. If you don’t get this warning, you can find Disk Utility at Applications/Utilities/Disk Utility.app
  4. Select the SSD from the list on the left side of the Disk Utility window and Click on the Partition tab.
  5. Select “1 partition” for the Volume Scheme, set the format to “Mac OS Extended (Journaled)” and give the drive a name. You can then click the “Apply” button to format the drive.
  6. Once the drive is formatted and shows in the Finder, you can then shut down.
  7. Restart to the OS X Recovery Partition by holding down Command-R until you get the Recovery Partition’s main window.
  8. Enter Disk Utility – since the SSD is in an external enclosure, you don’t need to worry about Disk Utility trying to create a Fusion drive.
  9. Click on the SSD in the list on the left and select the Restore tab. Drag the original drive’s icon from the left onto the “Source” field. Do the same with the SSD into the “Destination” field.
  10. Click the Restore button to copy all your data over to the SSD, then shut down.
  11. Restart holding down the Option key. Select the SSD/External drive as your boot drive and continue.
  12. Use the Disk Utility in Applications/Utilites to format your hard drive as desired.
  13. Shutdown, remove your SSD from the external enclosure, and install it in your mini.
  14. Once the SSD is installed, you should restart the mini and login. Go to to the Startup Disk preference pane and select your SSD as your boot drive.
  15. You can now use your Mac mini normally.

No matter which method you use, once you have both an SSD and a platter-based drive installed in your Mac mini, you should not use the Disk Utility in your Recovery Partition on those drives; it will see those drives as a “broken” Fusion array and try to repair it, destroying your data in the process. 

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    1. Jonathan says:

      Great tips,.. Ok I have 30 day old Mac mini with latest Mavericks pre-installed, have purchased data doubler Kit, and Samsung evo SSD. Everything is backed up to Time machine, but even so, I just haven’t added anything to the mini that it didn’t come with.

      I intended to create a fusion drive, have read several articles, and have have notes on how to name each drive and create the fusion drive in detail. However, if mavericks will create a fusion drive automatically by booting to the newly installed SSD and HD, what is the benefit of going into all of that detail? Basically I want a fusion, I have a good, small backup in Time Capsule, what would be the difference in letting Mavericks think its “repairing a fusion drive”, or me creating my own?

      • OWC Alex says:

        That is an excellent question Jonathan. Allowing the computer to “repair” the fusion volume using the new drives will work just fine. The only caveat is that the SSD needs to be in the upper bay in Disk Utility and the HDD needs to be in the lower bay to make sure it works properly. Just to clarify, the upper bay is the one closer to the top of the computer’s chassis, the bottom bay is the one closer to the big, circular foot pad of the machine.

    2. Pat says:

      Thanks for the great tips Chris. I tried to wing it and on the fourth try I found this page and your directions worked great. My plan was to buy an external drive to run the system and backup before the mini goes back home to mostly be gutted and refilled under warranty and then install the SSD after return. I installed a fresh version of the OS (3.56+ download hours yuk!) and the installer asked if I wanted to transfer files and apps etc, clicked yes and it was done in ten minutes. That was nice. The problem is that as I take personal junk off the old hard drive, they disappear from the usb connected SSD also. Got any suggestions to unlink these drives or what is going on?

    3. Patrick says:

      I am contemplating adding a SSD to my mac mini using OWC DATA DOUBLER.
      My concern is I purchased the mac in april 2013 with OS X Mountain Lion and have since updated to OS X Maverick 10.9.1 I do not know if the OS X was 10.2.1 when purchased.
      Would it be advisable to follow the instructions in the special note for adding a SSD to a 2012 mac mini to be safe?
      I will back up all data to a external hard drive before commencing.

      • OWC Ben says:

        You will definitely want to follow the above steps if you do not wish to end up with a Fusion drive. 10.8.2 was released in the Fall of 2012 so your machine would be affected by this.

    4. Steve Bohrer says:

      I got a Mini in Jan 2103, and added your data-doubler with a 128 GB SSD right off. I originally followed the install notes above, to avoid accidental fusion drive creation. I’m now at 10.8.5, and thinking about the free Mavericks update. So, most importantly, is there anything to be concerned about with the standard “download and install” Mavericks update? (As far as I know, the update does not use the recovery partition boot for anything.)

      Beyond that, is there any way to update the recovery partition on my disks to resolve this issue? Feels kind of like a time bomb waiting to fuse my drives, (though I guess it is unlikely that I’d ever inadvertently start up in recovery mode.) That is, is this still an issue with Apple’s current OS recovery partition: does it still assume that SSD+regular HD == broken fusion drive; or, do newer versions of the OS accept both valid drives as an okay state?


      • OWC Eddie says:

        As with any update we do recommend backing up your drive(s) before doing any upgrades or updates.

        Downloading and updating your Mac Mini current Operating System drive to Mavericks will not force your drives to become Fusion.

    5. Alex says:

      I just ordered a new Mac Mini and received your Data Doubler Kit. The mac mini model I purchased has a single SSD only and not a Fusion drive. I bought your kit to have 2 SSDs.

      Do I still need to follow these instructions?

    6. James says:

      Hi – how can I tell whether or not my 2012 Mac Mini shipped with 10.8.2? I bought it from Best Buy in September but for all I know it could have been sitting in stock for the past year. Am I understanding correctly that if I can verify that it did not ship with 10.8.2, then I can just install the drive and format it through Disk Utility without it erasing the data on my original drive? Thanks!

      • OWC Ben M says:

        10.8.2 came out in September of 2012, if you bought your Mac Mini in September of 2013 it is very unlikely it came with 10.8.2 or earlier. The safest thing to do is assume it came with 10.8.3 or later and follow our steps outlined in the blog.

    7. Jorgen Aage Jensen says:

      Can you suggest a replacement software for Disk Utility in case such a tool is necessary?

      • OWC Ben M says:

        Drive Genius is a great piece of software that will allow you to format drives. It has a few other features that come in handy for Hard Drives as well. It does have a defrag feature that should never be use on SSD or Fusion drives.

    8. Sel says:

      So once I have the SSD and a platter drive, how can I reformat the SSD without taking it out? I already have the OS running from the SSD (and not OS on the original internal drive) but I want to erase the SSD and do a complete install again. If the Disk Utility is not usable, what method can I use? Thanks.

      • OWC Michael says:

        You just cannot format the drive you’re booted from, so you can either install the OS on the platter drive and boot from that or Boot from an external drive in order to reformat your SSD.

    9. Doug says:

      Have just purchased OWC ‘Data Doubler’ SSD/2.5″ Hard Drive installation Kit for 2012 mini mac. Going to proceed as follows have current hard drive formatted with partitions:
      1. OS drive 200GB operating system,
      2. Music 250 GB itunes and all music related files
      3. Data 290 GB all data related
      4.Video 250 GB video related, processing
      Want to use SSD drive for processing of video (Blackmagic) and OS and do not want SSD space filled up with files that need for processing video and music (fusion drive). Plan on installing SSD format it as required and then using Carbon Copy Cloner to move OS drive to SSD? Would like to split SSD and use one section for OS and other for Video and Music processing. I clone for major backups and use Time Machine too. Do you see a problem in this procedure? Looking to get fastest SSD speed for Blackmagic to operate at highest video settings.

      • OWC Ben says:

        The partitioning layout sounds good. With the amount of partitions you’ll be setting up, I would recommend following the “external” method we outline in the blog. We do not recommend restoring from clones, we only recommend clean installs and using migration assistant to copy information.

    10. Rich says:

      I learned from you guys what Apple could not tell me in over 2 hours on the phone with support. Bungled my install and learned how to get the SSD identified again by comments in this blog. Thanks!

    11. John says:

      I have a Mac mini 2.3 I5 of early 2012 vintage around February or March which originally had Lion but then I upgraded to Mountain Lion. I used Time machine to move stuff over from my previous computer. I installed the ssd and kept the factory hd. Followed all the directions and updated the software. Upon migrating to the ssd i chose not to move over my music and videos. The initial time frame for migration was 5.5 hours which later moved to 1.5 hours which seemed rather short. My computer now shows Lion as the operating system despite my having upgraded the os. I’m missing photos from the last few years and the second hd isn’t visible. How do I recover from this state? I can fit all my data on to the ssd. Should I do a time machine restore? How do I recover the “lost” HD?


      • OWC Ben M says:

        In cases like these, where we don’t exactly know why information is missing or not where it is suppose to be, it is recommended to simply start the process over.

        You will want to be sure to erase the SSD before attempting it again. The time machine restore is the best option.

        If your HDD is still not mounting you will want to check the cables going to the hard drive, when you were installing the SSD they might not have been reconnected all the way or came loose.

        For more detailed troubleshooting or if you continue to experience issues please contact
        our tech support

    12. Lucio Bucio says:

      Thanks a lot, i has that combination of elemments, and my… (my wife’s) mini was in coma; thankfully it was brand new and didn’t have any important data. I found this article after everything had happened, after that the Disk Utility in the Recovery Partition won’t see either the hard disk neither the SSD. If anyone is in the same situation, what i did was unscrew the fan and the wifi “holed” base and carefully disconect the HDD, then start the recovery, and now you can use the Disk Utility to format the SSD and reinstall OSX on it (you have to be conected to the internet), it takes one and a half hour, once you see the desktop again, turn it off and conect again the HDD, turn it on and use the Disk Utility to format the 1TB HDD and you got it. Now my cuestion: is it is worth it to make a fusion drive instead of having the ssd with the OS and programs and the HDD for data?

      • OWC Michael says:

        There’s three basic setups that you can do with a SSD & HDD internally.
        1. Use the SSD to keep your OS and system files, while keeping your data on the separate disk. You can set this up seamlessly by following the instructions in our TechKNOWlogy video here.
        2. If you have enough space on your SSD, keep that as the main drive and use the HDD as a completely separate volume (like having a permanently-connected external drive).
        or 3. Setting up a Fusion drive.

        There are definite merits to each.
        The Fusion gives you a seamless way to let the OS store your data, but there is an increased need for current backups as if either drive fails, it will corrupt all the data on both drives.
        Keeping the drives separate means you have to manage which data is stored on which drive manually – which can be good or bad depending on how you’re using it – but it means that you decide where the data will be stored, not the OS.
        Relocating your home folder to the HDD and keeping system files on the SSD will speed up the overall system, and in case of drive failure does not affect the data on the other drive.

        • Jamie says:

          Do the same steps in that video apply to Mavericks? I’m having a hard time finding any info on setting the SSD as the OS drive and keeping the HDD as the home folder.

      • Alfredo says:


        I just had the same happening to me. I am a new Mac user with a brand new Mac Mini. I have installed the second SSD drive, tried the OS Lion re installation and cancelled before started. Now the mini won’t boot to either drive. All I get at start up is a blinking folder with a question mark in it.
        Can you elaborate on how you got your comatose Mini to come back to life?

        Thanks in advance,

    13. Peter says:

      Article left me slightly confused:

      Is there any reason why I can’t format both drives, and install a fresh copy of OSX from a USB installer?

      This article seems to make a BIG deal out of transferring data. If I’m starting fresh, can proceed as normal and not have to bother with Internet Recovery.

      • OWC Ben M says:

        The only supported USB installer would be an external hard drive with a recovery partition from another Mac OS X install or creating a stand alone recovery partition using this utility – http://support.apple.com/kb/dl1433.

        The primary focus of this blog is to make sure people do not accidentally delete their information and unknowingly creating a fusion drive they do not want. If you do not wish to preserve the data on the drives and do not wish to create a fusion drive you will still want to follow the steps above.

        • Jim says:

          #1: I don’t like fusion drives in general – they’re slow as molasses in data management.
          #2: I followed the guidelines included with my OWC Data Doubler kit for Mac Mini, using the SSD as the primary and the 500Gb “Apple” hard disk as strictly a data disk. So I basically downloaded the Mountain Lion OS on the SSD, migrated the contents from the hard drive, wiped the hard drive after the migration and re-partitioned it as a single partition named “Data”. I then made that drive sharable so the Mini becomes a data server to my other Macs for photos, music, etc., eliminating the need to purchase additional icloud space from Apple.
          #3: Using the SSD as the primary, boot up takes about 7-8 seconds and internet is much faster. Worth the price and effort!

          Hope this helps!

        • Peter says:

          I still don’t get it, Ben. Why can I not simply install a blank SSD in to the open bay, boot from USB image of OS X, go into Disk Utility, format both drives, and install OS X on the SSD?

          I have done this with Macs for years. Why is this suddenly NOT the way of doing things?

          • OWC Ben M says:

            If your USB image of OS X was created with the utility I linked previously you can do what you normally do. This article is warning if you were to use the built in recovery partition (not a USB drive) it would force the new SSD to be made into a Fusion drive with the original HDD.

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