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

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. 

OWC Chris S.
the authorOWC Chris S.
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  • hey OWC,
    I just installed a new 1tb SSD in my 2012 mac mini, bc the original HD was bad and crashed. I had a tech recover my files, and put them on my external GLYPH. but after replacing and turning on the mini, i get the flashing (?) folder..
    Whats the best or correct way to format, and replace OS X High Sierra to put my files back onto the new SSD??

  • Hi Folks

    I was thinking of adding my spare 250GB SSD to my mac mini 2012. However, I am already running a 1 TB SS/HD hybrid drive in there just now. Is it possible, or worth it to add the second drive?
    Thanks for your help in advance!

  • Hi there.
    I recently purchased a 2012 Mac mini i7.
    The plan is to install an SSD and a separate Tb hard drive internally.
    The unit came with high sierra, but I plan to go back to Sierra because of different filing systems.
    I am glad I came across the comments here. This will hopefully help me to successfully get my system up and running.
    My question is, what is the easiest way to back up a Mac Mini with two internal hard drives?
    Normally, I use time machine and do regular clone backups.

  • Hey Guys.
    I just added the SSD to my 2012 mac mini.
    Reinstalled the OS X (mountain lion) and formatted the HDD (just like in this tutorial).

    Strange here is… the boot time of the OS….still the SAME when the OS was in the HDD….Really SLOW (like 90 seconds of gray apple logo screen)

    THe funny here is SSD is working fine. The data transfer is Fast, as you expect from an SSD. Is just the booting time what buggs me.

    Any one has an idea why this occurs? any suggestion to improve boot time?

    • Well, that’s weird. Is it a “Fusion” setup or are the SSD and HDD two separate volumes? If separate, is there a chance that the OS is on the HDD by accident? I’ve done stuff like that before :(

      The first boot will be slow (long explanation) but subsequent ones should be very quick. They are on mine (separate volumes; music on HDD, everything else on SSD)

      • PETER
        No. I´m pretty sure I installed the OS in the SSD…and the HDD was formatted (again, I followed this tutorial step by step).

        Having said that, when I go to System Preferences in ´Start up disk´ appears an interrogation symbol (?).
        However, When I click to see only 1 drive appears (my SSD)


        I restarted but everything still the same. The mac mini takes like 1:30 minute to start up the OS.

        Maybe something went wrong when I choose the option to import your data from another drive?

        • Taking 1:30 to start really is strange. It does seem that you’ve followed the procedure correctly though.

          Try this: restart the Mini and hold down the “option” key. This should show you a list of bootable volumes. Choose the SSD and see how long it takes. That would be useful info.

          • Seems to me that if both drives were installed at the same time the OS installation interpreted you were doing an installation in a fusion drive format and that’s why you see only one drive. The install combined both drives as one.

            • In a fusion format I believe the OS is installed in the regular HD and the SSD part is used for frequently used apps to accelerate the boot times of than program in particular

              • EDWIN
                I dont think its possible. As I mentioned, after re-install the OS in the SSD, I proceed to format the HDD.

                I can see and use both drives from the finder.

                But when I enter to Preferences/Start Up disk, I only see the SSD. (photos in previous message)

    • More or less is the same thing that happened to me with the first SSD I put in my 2012 Mini. Strange thing I also had troubles opening apps that took more than usual to open with the SSD than with the HD. After reading a lot about it on the web I resolved my problem with an app, had to buy it for $20, that worked with TRIM. In my Mini TRIM was off and after activating it problem solved. It should take between 12 and 15 secs to boot up. Hope this help.

      • That’s puzzling. I am at a loss to know why TRIM would have an impact on app-launch time. Or boot-time.

        I did activate TRIM when Apple started supporting it for non-Apple drives (Yosemite?). But I wasn’t having app-launch or boot-time slowness either before or after. Note: my SSD is 1 TB, so is HDD.

      • EDWIN

        Well, my problem is not with the Apps. As I mentioned, the SSD works fast to write and read….is just it takes the same amount of time to start up the OS (90 secs, just like my old HDD)

        Whats TRIM? do I have to code that?
        And why this tutorial never mentioned?

        BTW, my SSD is a Sandisk Ultra II 240 Gb.

        • Nevermind. Already solved.
          What I did was disconect the HDD and re-install the OS with SSD only. Then reconect the HDD and format and woala! :)

  • I may be totally naive (I’m by no means a Mac / computer expert), but why can’t you simply unplug the existing (old) drive in the the top bay, install the new SSD drive in the lower bay, follow the far more simple upgrade options and call it good? In other words the old drive would just sit in the chassis as a dead component and the mini would be up and running on it’s new SSD.

  • If booting to external ssd OS drive. Is it okay to reformat the pre installed internal drive on a mac mini if I have a bootable USB Install Drive?

  • Can I assume using a bootable flash drive to install the OS on the new SSD will cause problems (in lieu of using the internet to install the OS)????

    • I do not see why that would be so. I did mine from a bootable USB external drive (HDD, not flash) and had no problem.

      I wasn’t installing the original OS though – I was installing El Capitan.

    • Hello Mark,

      Thank you so much for your question! Using a bootable flash drive is a great option for putting a new OS on a new drive! This being said, if there is ever any corruption on that USB drive, it will be transferred onto the new drive as well. If you fresh install the OS onto the USB drive every time, you will not have any problems!

      The safest way to download an OS would be to do an internet recovery!

      If you have any further questions, please feel free to contact our Technical Support Team!

  • Hi, I found this blog after having problems with my 2012 Mac Mini after installing an SSD drive and creating a Fusion Drive. After many attempts, I was able to get it working but since then, my Mac keeps crashing and I’m losing hope that this DIY Fusion drive setup is going to work for me. I’ve looked over your article but don’t see anything special regarding setting up a Fusion Drive except for the part about setting up a Partition on the SSD drive. Can someone tell me of I’m missing something. This article looks like a setup for a separate SSD and HDD. Thanks for any clarification you can provide, much appreciated

  • I’ve just read this article and the entire contents thread and I’m still confused. I would like some points clarified, if possible.

    I have a refurbished 2012 MacMini that I bought in late 2014. I don’t remember which OS version it came installed with. I immediately re-formatted the 1 TB HDD (in the “lower” bay) and installed OS X 10.9.5. The recovery partition also contains OS X 10.9.5.

    I now have the OWC Data Doubler kit and a 1 TB Sandisk SSD. I’ve reformatted the SSD and installed El Capitan (OS X 10.11.x) on it. I’m going to install the SSD and use it as my boot disk. The HDD in the second slot will be used as a clone backup. I will *not* be making a Fusion drive.

    Does this “special” problem affecting the 2012 Mac Mini still apply to my system since I’ve reformatted the original drive and created a new recovery partition? And if so, will it always apply regardless of the version of OS X and recovery partition installed?

    If yes, can I avoid this problem by installing the SSD in the “lower” drive bay and moving the original HDD into the “upper” drive bay?

    Why is only the 2012 Mac Mini affected by this behaviour?


    • I am giving up on trying to create a DIY Fusion Drive on my late-2012 Mac Mini. I have read countless horror stories around this and after 4 days of following all kids of advice and dealing with constant system crashes and restarts, I’m going back to the way it was. This whole ordeal has been way more trouble than it was worth

    • Hello Vic,

      Great questions! Updating the OS should update your recovery partition. I would however recommend to follow the instructions in the article just in case.

      When upgrading a drive or changing out a drive in a 2012 MacMini it will be best to follow these instructions to ensure that there will be no data loss. It will not matter what bay the SSD is in.

      If you have any further questions, please contact our Technical Support Team!

      • Question: I have the mac mini 2012 model with a Ssd and normal drive on both drives is Mountain Lion installed and i am booting from Ssd > can I safely do an os upgrade to Sierra ?

          • Hello I meant can I do the upgrade from mountain lion to Sierra > Do I not get in trouble that then my disk will be damaged during the fact that i have an SSD and normal HD and the system want to make it a fusion drive?( see article above)

            • I have this exact same setup (SSD + HDD, not Fusion) and had no problem. There was no suggestion that it wanted to try Fusion on them.

              The SSD on mine is bootable, the HDD is data-only.

              • I have done this as well: Samsung EVO 850 in lower drive bay (original hdd location) and Seagate 2tb in the other bay. Kept them as separate drives. I’ve been getting kernel panics on startup after upgrading to Sierra. Messages like “OS not set yet”. No issues when running Mountain Lion or EL Cap. I have done so much troubleshooting I don’t know what else to do. I’ve run all the diagnostic tools that I can find. I’m not confident that Sierra is working properly with third-party disks. Is anyone running Sierra smoothly with third party disks? Or is this a new level of proprietary tyranny from Apple?

  • Is there a version number of the Disk Utility app we can just check to know if it is the version that will try and repair a new install thinking the two drives are one fusion drive? I’ve got a Mac Mini 6,1 that I picked up used and have no idea what OS version it came with.

  • a follow-up to my Nov 27 post:-

    I installed the two-drive upgrade without any major issue. It was not a quick job by any means but OK if you have the right tools and are patient. One note – a couple of the screws labeled as T-8 are actually T-9 (the ones attaching the drive to the antenna grate)

    I configured it as a Fusion drive using “Terminal” and “diskutil coreStorage” command-line stuff. No drama. Simple.

    Installing OS X (El Cap) went OK until there was one second left and stayed there for a l o n g time (I was installing from a local hard-drive installer, not Internet). Then I migrated my data from the backup copy. In my case, I couldn’t migrate from the old drive as it was a Fusion drive, not a single drive. So I’d made a separate backup and migrated from that.

    A day or so later I reconsidered my setup, realizing that the majority of my data was music (iTunes library) and that doesn’t need to be on SSD. So I reconfigured the drives, eliminating the Fusion lvg and reformatting as two separate drives. The iTunes library went on the HDD and everything else on SSD. This is now working very nicely.

    A few notes on the installation process:

    – everything is tight. I looked at the installation videos. The details on iFixit were helpful especially because there are still photos and it’s easier to identify exactly where the screws are. The videos are great though because it shows exactly how the sequence proceeds

    – my system came with a Fusion drive and so everthing that was needed was already in place. For the 2012 Mini, the SSD is a standard format 2.5″ drive. Later models are different, but the 2012 is an easy upgrade. All the cables and screws are already there. You just need to move them from the old drives to the new ones.

    – there are no temperature sensors on this model. Earlier models, such as 2010 Mini, had some but these are external and can be transferred. For the 2012 though, this isn’t an issue.

    – both drives have insulation stuck on them, even the SSD which has no exposed circuitry. You can peel these off by gently lifting on the sides and then reapply to the new drives. For the 2010 Mini, the temperature sensors are attached to these plastic sheets. For the 2012 there are no sensors

    – it can be hard to get the “bottom” drive (closest to you as you work on it, but the bottom one when in operation) located into its mounting points. This is easier if you tip the mini onto its front face (the one opposite all the connectors) so that the drive goes in vertically. Slip a business card underneath it when you re-seat the motherboard – this will help get the screws (from the antenna grate) to go in properly

    – you don’t need to fully dismantle if you’re not changing the “upper” drive (the one deepest in the case). But you still need to pull the motherboard out a bit to get clearance for the drive to come out

    – the Apple HDD was in the upper (deepest) spot and the SSD was lower (closer as you work on it). I placed the new drives in the same configuration

  • I have a late 2012 Mac Mini and I was having the hardest time installing OS X with the HDD in the “Original” spot and the SSD using the data doubler from OWC. Even when I got OS X installed on the SSD, rebooting would show the “no smoking” symbol and I could not get back into OS X. I finally solved it by switching the 2 drives position, and voila it works amazingly. I also created a bootable OS X El Capitan installed to skip the Internet Recovery load time (which was always trying to force me into a Fusion Drive). I hope this helps someone!

  • I have a 2012 Mini (Macmini6,2) that came with Apple’s Fusion drive and I’d like to upgrade it. I am thinking of the Mercury Electra 6G SSD 1.0TB and WD Blue WD10JPVX. OS X 10.11 El Capitan is installed. I guess that the new system will be a Fusion drive, but either way is fine from my viewpoint.

    If I understand the (very helpful) comments and suggestions correctly, I should install the SSD in the upper slot (deepest into the Mini, working from the bottom) and the HDD closer to the antenna grate.

    Q: do I need a “Data Doubler” or any extra cables, screws, grommets etc? Or are the existing items suitable?

    Q: after installation, do I just boot into recovery to format the drives and create a Fusion drive? Is anything else needed? Is it better if I format the two drives first? Or should I not do that?

    • Hello Peter,

      You will need the OWC Data Doubler in order to properly install two 2.5″ SATA drives in your MacMini 6,2. Depending on where the original drive is located will determine what kit you will need. If your drive is located in the “lower” bay, you will need to purchase the OWC DIY Installation Kit . If your drive is located in the “upper” bay, you will need the OWC ‘Data Doubler’ SSD/2.5″ Hard Drive installation Kit.

      When you have installed both drives into your MacMini, you will need to manually create the new fusion. For further instructions, please reference OWC blog article “Creating your own Fusion Drive”

      If you have any further questions, please contact our Technical Support Team!

      • Follow-up answer to my earlier question.
        (1)if the Mini originally came with Fusion drive, then everything needed is already there. Data Doubler is NOT required.
        (2)I originally created the setup as a new Fusion drive, but then thought better of that and re-did the setup as a boot drive(SSD) and second drive(HDD). This worked for me because I have lots of music and put all that on HDD. Everything else is on SSD.

  • Curious if anyone has tried doing a fusion drive? I am guessing that most of us would prefer to know what is where rather than letting OSX manage things? And with bigger ssd’s fairly inexpensive it seems like the benefits of a fusion drive setup are minimal?

    I’ve got a 256gb 840 evo ssd and the stock 5400 500gb hdd. Trying to decide what to do with it all. No data of any value as this is just an htpc.

    • I did a fusion drive (120GB OWC SSD + 1 TB apple HDD) and it worked out fine, until the drive was getting over 90% full, it lost the performance boost it used to have. I’ve since changed it to a 960 GB SSD and 1 TB Apple HDD non-fusion, and I like having control over what needs to be fast.

  • About a month ago I bought a new Mercury Pro 6G SSD for my 2012 mac mini as an upgrade for the main drive. It was a nightmare trying to do a clean install or an internet restore. Never couldn’t do it because every time it was in the last couple of minutes of installation an error always came up. Ended up doing a restore from the main drive as this was the only thing that worked.

    The boot up process was a fast as advertised. But after 10 minutes of using it and opening several apps noticed that the system became very slow, unreliable and the multicolor ball of doom started to appear a lot, taking longer than usual for an app to open.

    Read a lot on the internet about similar problems, but nothing sims to fit what I am experimenting with my mini. I don’t know if this has to do with try TRIM thing or something else. The SSD firmware is up to date.

    Thanks God I have not formatted the drive I removed as I plan to reinstall it in the mini and using the SSD for an external drive.

    Any help or advise please.

    • Just a couple of things to try.

      Repair permissions.
      How much memory is installed, is it all recognized in system report?
      Run a disk speed test (many free ones in internet)
      Does system report see the MercuryPro at 6GB link speed?

      • Mini i5 with Yosemite and 16 megs of memory. Did all you mentioned several times. The SSD is recognized fine and the speed tests gives the specified 6G speed the SSD was advertised. But every time the same thing happen. Boot up fast, start working fine, but after several apps openings and between 10 and 20 minutes the ball of doom appears taking more than usual to open, close or move between apps. Do a shut down, restart and the same thing happen. I am frustrated as I didn’t buy an SSD to convert it to an expensive thumb drive.

    • Update: after looking and reading a lot of articles on the internet about SSD on macs and doing all the diagnostics and permissions fix on my drive I decided to try a very cheap program to manage my HD’s. What I found out was that TRIM was disabled on my Mini 2012. After enabling it all the problems were solved. Now I get all the speed of the SSD without the ball of doom appearing every time and slowing all apps. Maybe this will help other with the same problems.

  • You’re pretty clear that one must follow this special method of formatting the new SSD IF the original OS was 10.8.2. I bought this Mini with Mountain Lion, then upgraded that to Mavericks and finally Yosemite.
    1 — how would I determine if I had 10.8.2 originally and not 10.8.1, 10.8.3, 10.8.4, etc. ?
    2 — Is the Recovery HD not recreated with each installation of a newer OS X version?
    3 — How would I proceed if I actually wish the new set of drives to be formatted as a Fusion drive?
    4 — following the successful installation and formatting of the new SSD, the OS will be 10.8. Is it necessary to upgrade that to Mavericks, or may 10.8.x be directly upgraded to Yosemite?

    • OK, I checked the System Report/Software/Installations and found that the there was an upgrade to 10.8.3 the day I set the Mini up, so I DID start with 10.8.2. Question 1 is answered. I’d still like to know about 2 – 4. Thanks in advance.

      • Hello Ron,

        The Recovery HDD should be recreated with each installation of a newer OS X version. But in reality it will only recreated if you format the drive, then install to it. If you simply erase the OS, then install the OS from the recovery partition on that drive you won’t get a new recovery volume.

        If you are wanting to proceed with setting up your new drives to be Fusion, please take a look at this OWC Blog Post on “Creating your own Fusion Drive”

        If you are looking to run the drives individually and you have successfully installed and formatted the new SSD, all you will need to do is upgrade directly to Yosemite. You do not have to upgrade form 10.8.X to 10.9.X.

        If you have any further questions please feel free to contact OWC!

  • I installed an SSD in my 2012 Mac Mini, which is in addition to the original HDD. Using the OS Recovery Partition, I reinstalled a new OS X on the SSD and migrated my applications from the HDD to the SSD. All data is stored on the HDD. (I did not delete the OS X and applications from my HDD.)

    Prior to the installation of the SDD, the HDD had been backed up to an external drive using Time Machine. I want TM to only backup the HDD (not the SSD) and inherit the HDD history. Do I need to change any settings in TM, e.g. tell it to inherit the HDD history? Currently, I turned TM off.

    (I rarely add new applications and can always keep the OS X and applications in the HDD by making the HDD the start up disk.)

    • Time Machine, by default, backs up all the drives on the computer. You can alter the settings, though, to exclude any drives you don’t want to back up. You can find the current version of the instructions to do so from Apple here.

    • Hello Lukas,

      Here are the instructions to format the SSD that is installed in your computer:

      Restart your computer and boot to the internal hard drive like normal.
      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
      Select the SSD from the list on the left side of the Disk Utility window and Click on the Partition tab.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.
      Once the drive is formatted and shows in the Finder, you can then shut down.
      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.
      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.
      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.
      Follow the prompts to install.The actual downloading and installation process may take a while.
      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.
      Once the migration is complete, your computer should boot to your SSD.

      If you have any further questions please contact OWC!

  • First Question:

    I will be installing an SSD into my late 2012 MacMini 2.3 i7 using the OWC data doubler I just received. The HDD has 10.10.3 installed.

    In the Important Note, there appears to be an action that needs to be taken between Internet Restore Method step 8 and step 9.

    (8. Restart to the OS X Recovery Partition by holding down Command-R until you get the Recovery Partition’s main window.
    Note: 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.
    9. Select the option to “Reinstall OS X” and select the SSD as the target disk. The installation process will take some time.)

    Am I closing a window after step 8 and then opening Disk Utility from the HDD?

    Second Question:

    If I keep the latest version of Yosemite on the SSD, and install an earlier OSX on the HDD (e.g. Mountain Lion), can I just migrate my Applications and Library folders to the SSD, but keep and share my documents in the same User folder on the HDD?

    • To answer your first question, please format the drive before booting to the Recovery Partition. Though unnumbered, this is steps 4-6 in the first set of instructions at the start of this blog post.

      Since the HDD is being treated like any other drive without an OS when you are booted to the SSD, you can keep your data on it and access it while booted to either the SSD or HDD.

  • Hi, I have a MacMini 6,2 with OS 10.8.5. I bought the data doubler a couple years ago and set it up so the OWC SSD has the OS and the old internal drive is used as a work/storage drive. Not a Fusion drive.

    This setup was working flawlessly since I installed it. Until I rebooted the other day and wham! The MacMini won’t detect any bootable OS. I did a standard restart. No buttons being held during the process. Fortunately, I was able to Target disk mode to both internal drives and backup.

    What would cause this after years of perfect use and nothing different happening? Does it matter which SATA port on the motherboard the OS drive is connected to?

    I removed the secondary spinning drive and I am now reinstalling the OS on the SSD only. I’m too scared to put the second drive back in.


    • When installing an SSD or HDD into a MacMini, it does not matter what SATA port on the motherboard the OS drive is connected to.

      This may have been caused by a corruption in the Operating System (OS). I would recommend doing a fresh install of the OS. If you have any further issues with it, please feel free to contact our technical support team.

  • Installed the new SSD in one of our 2012 i7 Mac Minis with no issue. One of my helpers offered to finish formatting the new SSD. I’d cautioned him about not creating a fusion drive. By accident he did. Followed the MacWorld instructions to split out the SSD from the HD. Disk Utility can see the original Apple HD, but not the SSD. Any suggestions?

    • A Fusion drive will show up as a single volume. When looking in Disk Utility you will only be able to see the single volume and the name that was provided to it.

      To make sure you have successfully created a Fusion, you will want to look in Disk Utility under “Type” and make sure it states “Logical Volume Group”.

      You can also go into “About This Mac” select “System Report” and then under “Hardware” select “SATA/SATA Express”. You will then be able to see every SATA drive in your computer independently.

      If you are still not able to find the SSD or confirm the Fusion was set up correctly, please feel free to contact our Technical support team!

  • Hi,
    I just got an OWC SSD and data doubler kit. 2011 Mac Mini.

    – I currently have 10.9 installed on the original harddrive.

    – What I want to do is install 10.10 on the SSD (and keep 10.9 intact on the original drive).

    My goal is to have the original 10.9 bootable and a fresh new 10.10 bootable … and then pick which drive to boot from.

    So my question is:
    Once I install the SSD can I simply partition it GUID from within the 10.9 Disk utility (not the recovery disk utility but the OS disk utility) and then download and install 10.10 on it?

    And then use System Preferences / Startup disk to decide which drive to boot from.

    Will that be possible?

    • Hello Jason,

      This is very much possible. Once you install the new SSD, you will want to boot your computer as you normally would. You will then be able to go into disk utility and format the new SSD. Once the new SSD has been formatted you will be able to proceed with the fresh install of 10.10.

      Once both drives have operating systems on them, you will be able to choose what drive you would like to boot up off of and use. Please take a look at this Apple document for instructions on how to use and set this up.

  • Hi,
    I currently have a Mac Mini Late 2012 2.3Ghz server. I swapped one of the HDD and installed a Crucial SSD. It is running Yosemite perfectly, it is not in a fusion array.

    I have just purchased another Mac Mini server late 2012, this time a 2.6Ghz model with 1Tb Fusion drive setup. What I want to do is swap out the 120gb SSD that on the new Mac mini I bought and replace it with the Crucial SSD (512gb) that is currently in the 2.3Ghz model I have.

    So the question I have are
    1. Is this just a straight for swap out from the 2.3Ghz to the 2.6Ghz
    2. Does it matter that the O/S was setup in the 2.3Ghz, and should it work in the 2.6Ghz
    3. I read elsewhere that I should break the Fusion drive array through terminal commands before I put the new SSD I
    Many thanks

    • You will want to break the fusion drive on the 2.6Ghz model first and be sure the drive that will be staying in the computer is formatted and ready for use. You can then swap in the new SSD you want. Since both drives will be formatted and ready for use you will not run into an issue. It is only when you go into disk utility in the built-in recovery partition that it will try and force a fusion drive on you.

      Best practice of course is to be sure everything is backed up before beginning just in case things do not go according to plan.

      • Many thanks for the speedy response!
        If somewhere down the track could I look to setup a Fusion array with the new configuration? I am of the understanding that it will wipe all my data on both drives.
        Is this something I can do which will work fine without issues or would you advise against setting up a fusion drive with SSD components that are not factor?

        • You certainly can make the two drives become a fusion drive down the road if you’d like. The easiest way would be doing what we advise against in this article. Boot your computer into the built-in recovery partition and proceed to Disk Utility to format your drives. It will automatically erase the information on both drives and create a fusion drive for you at that point.

  • Hi,
    First thank you for that description, I got a new Mac mini with all three In your article mentioned factores. It helped me. Now I updated Yosemite on my SSD, after I installed via Internet Recovery mountain lion. I got no OS on my HDD. Only updated Yosemite.

    To my question:
    I got a updated Yosemite OS on my SSD now, it is not a fresh/clean one.
    How can I make a clean installation of Yosemite on my SSD, without using the recovery disk-utility-management? Backup is not required, cause no important data on Mac.

    Greetings from Germany

    • By clean installation I mean a new Yosemite installation from zero\nothing on my disk. The opposite of a updated installation. I read about the USB method, but will it be possible WITHOUT using the version of disk utility in the recovery partition?


      • Hi,
        I just did it =) thanks for this Tutorial. I have a Samsung 840 evo 120 GB SSD and had problems with installing Yosemite or another OS in my Mac mini late 2012. Finally I made it! The problem was the data doubler/data cable. If you want to use your SSD for your Yosemite OS X, YOU NEED TO USE THE ORIGINAL DATA CABLE / SATA CONNECTION CABLE WHICH IS USED FOR THE HDD.
        Only with those two conditions it will work without problems.

        Hope this helps

        Greetings from Germany

  • I have a Macmini6,2 with Mavericks (10.9.5) factory installed with a regular internal hard disk in the lower bay.

    I cloned the internal drive to my SSD via the “external method,” using the recovery partition’s Disk Utility in the factory installed hard disk. At this point, I’ve fixed disk permissions on the SSD and booted it up to confirm the internal drive was cloned properly.

    I just received my Data Doubler kit from you today, and read about this potential issue with the Fusion drive array setup.

    The goal is to make my SSD the main system disk and to use the original factory hard disk my secondary drive for data. I don’t want a Fusion drive array; I just want a discrete secondary drive.


    1) Does the procedure outlined in this post still apply to me (doesn’t sound like it?)?
    2) Does it matter which bay I install the SSD in if I want it to be the main system drive?
    3) Can I keep my OS/data in my old factory hard disk in my secondary drive?

    Just trying to be careful before I tear down my Mini and install the drive! :)

    Thanks in advance for your advice!

    • 1) Since you’ve already restored the HDD contents to your SSD, you do not need to worry about installing the drive into your Mac Mini.

      2) It will not matter which bay the SSD is in

      3) There are a few avenues to accomplish this. I go in depth in how I did it myself here. I mention and link the other two alternatives in that blog post as well if you’re interested in looking into them.

      The most important thing to remember is if you ever go to format the original HDD or new SSD while both are in your computer, it will try and create a fusion drive. If you ever need to erase and format one of the drives, you’ll need to remove one of them.

      • Yowza! I didn’t realize this issue was for “if you _ever_ format” either drive — I thought it was just a bug of the version of Disk Utility on the original 10.8 Recovery Partition.

      • Thank you for the response!

        Thanks to your Data Doubler kit and awesome instructions, I got my SSD installed and now my Mac mini’s disk access performance rocks!

  • It’s not clear if this special note applies to adding a 2nd SSD Drive to a factory built Mini (6,2 / 10.8.2) already configured with an SSD drive.

    After installing the OWC data doubler using a Samsung evo 500 gig to the lower tray and rebooting, the Mac will not boot into the existing 10.8 (factory installed 10.8.2 on 256 SSD Drive fully updated to 10.8.5).

    The drive showed up in the Disk Utility (that was available from the automatically started repair screen) with a green icon as an external drive.

    Booting from an external USB Mac build of Mavericks (and Yosemite) and using the Mavericks DU, I can’t even see that the factory SSD drive is present. The new 500 gig was clearly available.

    I formatted the 500 gig using the Mavericks DU and have started the recommended Internet Restore (command-R) now after auto reboot I get the blinking question mark screen…

    My Mini (6,2) is not the server edition. Will my system actually support two SSDs ?

    • Perhaps I have a loose connection… The Disk Utility showing what I thought was the factory SSD is version 13 (444). Looking closer “disk2” has a partition indicating “OS X 10.8.2 Base System, Disk Description: Apple disk image, capacity: 1.24 gig. It has a yellow icon and Mount Point: /

      The questions still stands though:

      Will the non-server edition of 6,2 mini support two internal SSDs ?

      • Opened the Mini back up… and found a LOOSE SATA Connection…

        The SATA connection must have become disconnected when I installed the wifi antenna.

        After reconnecting and booting up it launched directly into my existing 10.8 factory installed system… Both drives are clearly functioning..

        Thanks OWC for the great installation Video!

  • Am I correct in thinking that this is only an issue with certain versions of disk utility pre installed on the recovery partition?

    I’ve completely erased the HD (nOt just the partition) that came with the Mac mini and clean installed Yosemite.

    To erase a newly installed SSD can I do so by booting into Yosemite on the HD and using the disk utility installed there?


  • I recently bought the 120GB OWC Electra 6G and The OWC Kit for Mac Mini 2011 and 2012 2nd 2.5.
    I do not think I will have any problem installing the 2nd drive but my concern is transferring the system to the new drive.
    OS X 10.9.4 and the mac is the Mac Mini 6.2 with an i7 Processor at 2.3 Ghz.
    Does cloud already have this backed up or do I need to back it up to another drive?
    I guess once I get the 2nd drive installed then I will install the system on it?
    Do I keep or use my new drive for the system only?
    I already have a tool kit and the extra internal drive cable I guess it came in the bundle?
    07/04/2014 Order SO-8762530 Batch # 25594

    Steve Brown

    • Hello Steven,

      You may follow the instructions in this blog if you would like to keep your original drive and the new SSD separate drives, otherwise you’ll end up with a Fusion drive when you go to format the new SSD.

      If you prefer keeping your two drives separate you have two options for keeping your data and OS file separate. My preferred method was outlined in this blog
      and another method is outlined in our video here

      • Can this method work with a 2012 mac mini 256 SSD housing a OS X and Windows 7 Bootcamp OS and a single ExFat partitioned 1TB HDD? I want both OSs to have access to the ExFat HDD disk.
        Both successfully see the HDD when connected externally now. My fear is when I finally connect it internally that the bootcamp setup will be lost and it will try to create a Fusion Drive.

        • If you are not going to be reformatting either of the drives you have no risk of losing any partitions. The fusion drive is only forcefully created when formatting one of the two internal drives.

  • Hi! I have this issue so I booted from my USB installation and I’m installing base system on my SSD but it is taking a lot considering it is an SSD. should I worry? better to download everything from internet recovery? Better to swap lower with upper drives?

    • I’m sorry to hear it’s taking so long to install. It is possible this is perfectly normal; it all depends on what USB device you are using to install the operating system. If it is USB 2.0 based, then it is going to go very slowly even though you are installing to an SSD. If you have the option of a USB 3.0 device it will go much faster.

      If you are already using a USB 3.0 drive to install from, then I would suggest using the online recovery to try installing as the sluggishness may be indicative of a problem with the installer itself.

  • How can I restore to factory settings? I did upgrade to SSD and followed the above steps in 2013 when I got my mac mini. But how do I restore it to factory settings. Any help would be great

    • To restore you computer to factory default OS settings you’ll need to boot from an external drive to safely erase your SSD. This can be an external clone backup or a recovery partition on a time machine backup. Once you have erased your SSD from an external you may reinstall the OS from the built in recovery partition. This clean install of Mac OS will restore your computer to factory OS settings

  • 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?

    • 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.

  • 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?

  • 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.

    • 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.

  • Hi,
    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?


    • 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.

  • 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?

  • 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!

    • 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.

    • 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.

  • 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.

    • 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.

  • 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.

    • 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.

  • 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!

  • 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?


    • 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

  • 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?

    • 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.

      • 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.

    • Hi,

      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,

  • 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.

    • 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.

      • #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!

      • 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?

        • 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.