Creating your own Fusion Drive

One of the newest technologies available with the latest Macs is the ability to have what Apple calls a Fusion Drive. This is essentially a Solid State drive and a platter-based drive combined into a single volume. Apple’s underlying Core Storage technology then uses the SSD for the OS and frequently-accessed files, which will benefit from the speed, while placing lesser-used files on the larger, but slower platter-based drive.

The practical upshot of all this is that Fusion gives you roughly the performance of an SSD, while also taking advantage of the plentiful storage of platter-based drives. However, you don’t need to have a Fusion Drive from Apple to do this; with the proper command-line version of Disk Utility, you can create your own array with any platter-based drive and any SSD.

Of course, there are a few caveats to this setup (or the stock Fusion Drive, for that matter) that you should consider before committing to a Fusion setup. We’ll discuss those in a bit. First, though, let’s look at the process of actually setting it up.

Setting up a Fusion Drive

Items Needed:

  • A 2012 Mac mini – this is an absolute requirement as these are the only machines that currently have a version of Disk Utility that can create a Fusion volume.
  • A hard drive and an SSD installed/to install internally – Fusion is designed to work on internal drives only.
  • An external drive to clone to – creating a Fusion volume will erase both the SSD and the hard drive, so if you have information on the hard drive you want to keep, you’ll need to have a copy of that data elsewhere.

Step 1 – Make sure you’re up-to-date.

Make sure the OS on the mini’s drive is updated to 10.8.2 or later. This is absolutely necessary, as the proper version of Disk Utility for doing this is on 10.8.2 or later on the mini and you want the OS versions to match.

Step 2 – Have a copy of your computer’s data.

This process will erase both the installed SSD and hard drive, so if you have data on one or both of these drives, you’ll want to have a copy that’s not on either of the two drives that are going to be part of the Fusion array. If you are installing both a new SSD and a new platter-based drive into, you can put your original drive in an external enclosure, and your data will be there, out of the way. If you’re using the same drive that you already have installed, you will need to copy that drive’s contents to an external one.

Step 3 – Install the new drive(s) in the computer you’re upgrading.

See our video page for our step-by-step instructions on installing one or both drives into your mini.

Step 4 – Boot to the external drive.

We need to boot to the version of 10.8.2 that came with the Mac mini, but since you can’t erase the drive if you’re booted to it, simply boot to your clone by holding down the Option key at startup and selecting the external drive you cloned to (it’ll have the orange icon). Then, log in to the desktop like you normally would.

Step 5 – Open Terminal.

If you installed at least one brand new drive, you will likely get a message about a disk being unreadable. That’s okay; just click “Ignore.”  We’ll be initializing it over the next couple of steps.

You can then open Terminal. You can find it in Applications/Utilities/Terminal.app

Step 6 – Find Your Disk IDs.

In Terminal, type: diskutil list

This will have the command-line version of Disk Utility (diskutil) that lists all the disks attached to your computer. In the results, you will find the disk IDs of the HDD and SSD. Take note of these ID numbers. In most cases (2 drives internally and booted from the external), the IDs will be “disk0” and “disk1.” However, individual results may vary, depending on your setup, so you’ll want to make sure you have the right drives.

Step 7 – Create the Fusion drive array.

In Terminal, type: diskutil cs create drivename driveIDs

This is the command that actually tells your Mac to tie the drives together in a Fusion array.

Broken down, the step does this:

  • diskutil - the command-line version of Disk Utility.
  • cs - this invokes Core Storage, which is necessary for Fusion.
  • create - creates a Core Storage group.
  • drivename - this is the name of the drive and how you want it to appear in Disk Utility (not the Finder – that comes later). You can call it whatever you want; in our example, we named our Fusion array “Fusion.”
  • driveIDs - these are the drive IDs of the drives you want as part of your Fusion array, separated by a space. In our example, they are “disk0” and “disk1”, but it may be different in your setup.

Once you enter in this command, it’ll do its thing and set-up the drives into an array for Fusion.

Step 8 – Get ID information for Fusion array.

In Terminal, type: diskutil cs list

This will give you a listing showing any Core Storage Logical Volume Groups (aka Fusion Drive). You will need to do two things here. First, copy the long alphanumeric string for the Logical Volume Group, then note the Free Space for it. You will need both of these for the next step.

Step 9 – Format the Fusion drive so you can put files on it.

In Terminal, type: diskutil cs createVolume groupString jhfs+ volumeName size

This command creates a volume on the Fusion array where you can place your files. Again, since some important stuff is going on here, let’s break down the command.

  • diskutil - again, this is the command-line version of Disk Utility.
  • cs - invokes Core Storage functions, which are necessary for this arrangement.
  • createVolume - this is the command to create the actual storage area for the drive that is represented on your desktop by an icon.
  • groupstring - this is the long alphanumeric string you copied from the previous step. It identifies that the array you created as the one getting a volume placed on it.
  • jhfs+ – the format of the drive. This is Apple Extended Format (journaled), which is recommended for drives with an OS installed on it.
  • volumeName - the actual name of the volume, how it should appear underneath the icon. If there is a space in the name, you should either put the entire name in quotes (“Drive Name”) or put a backward slash before the space (Drive\  Name). In our example, we did the latter, naming our volume “OWC Fusion.”
  • size - this is the size of the volume. In our example, we had a 1.1TB drive. We used “1100g” to denote it as 1100GB (1.1TB in base 10). Alternatively, we could have also used 1.1T, or even 100% as a size.

Once you have this information entered, hit Return and let it do its thing; the Fusion Drive will then be available in the Finder.

Step 10 – Boot to your clone’s Recovery Partition.

Now that we have created the Fusion volume, we can now install the OS and bring over your data.

Boot to your clone’s Recovery Partition by holding down Command-R at start-up.

Step 11 – Install OS X

Once booted to the Recovery Partition, select the option to Reinstall OS X. Follow the prompts for installation, choosing your new Fusion Drive as the destination. You will need an Internet connection to do this; an Ethernet connection is preferable, though you will also be able to use an AirPort connection, albeit at slower speeds.

Step 12 – Migrate over your information.

As part of the setup for your new installation, you will be asked if you wish to import data from another disk; you will want to. Select your clone and Migration Assistant will bring over your data.

Step 13 – Enjoy your new installation.

Once migration has completed, shut down your computer and disconnect your clone. At this point, you will have OS X running on a Fusion drive on your computer. You can now use it like you would any other drive.

Things to consider before committing to a Fusion setup

As with any drive setup, there are pros and cons to a Fusion array. The pros, as mentioned at the beginning of the article are that it appears single volume and works automatically to keep the best speed. However, there are a couple of cons that you should also be aware of.

You will need a backup.

While a backup plan for your computer is something you should have anyway, this becomes even more important for Fusion Drive equipped Macs. The way Fusion is set up, if either the hard drive or the SSD fails, the data on both drives is lost. Having a reliable, frequent backup plan will be essential in protecting against data loss.

Performance may not be enough for high-end professional use.

Apple claims near-SSD performance for Fusion-equipped drives. For casual use (email, Web browsing, basic iPhoto use, etc.), this is largely true. From testing both in-house and by Lloyd Chambers of Mac Performance Guide, a Fusion Drive will first fill the faster SSD portion, then start filling the slower hard drive. Once writing is complete, data will be moved from the SSD to the hard drive until there is 4GB free on the SSD again.

The trouble comes when you start working with larger files, such as with pro audio, video and large-scale photo work. Often, these files far surpass the 4GB size, so you will see fast SSD transfer speeds followed by a precipitous drop in speed when it transfers over to the hard drive. For a full rundown of testing, check out Lloyd’s writeup at Mac Performance Guide.

For those that a Fusion Drive just isn’t going to be practical, you may be better served using a Hard Drive/SSD 2-drive setup with a relocated home folder. You reduce the risk of losing all your data at once, while still retaining a large portion of the speed/storage benefits of Fusion, but with more flexibility.


LEAVE A COMMENT

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  • Could you potentially use 3 or 4 drives this way if you used the proper drive names in terminal on a mac pro?




  • I had an issue that I not sure everyone is aware of. If you reformat and destroy the Recovery partition you are not going to be able to install one after the core storage is made. you must look at the drive when you do the diskutil list and make sure that you don’t use the entire drive for the CORE Storage. Instead you may see something like this..disk0..disk0s1 and so on in my setup my recovery partition is in disk0s3. Obviously disk0 is my SSD so when listing it you have to in my example list the drives like this diskutil cs create “drive name” disk0s2 disk1 that way you leave the Recovery partition intact. Otherwise FileVault and other service won’t work plus you will have to be sure to have a thumb drive with a OSX install on it.




  • I’m in the market for a new iMac, i am also considering the Fusion drive option and have a question. Could I order the 27′ iMac with 256GB or 512GB flash storage option and then add my own 2TB HD (in what i presume would be an empty bay) and create my own Fusion drive from those two? I know this would mean opening up a brand new machine which I would be loathed to do but in theory is this an option?

    Why do Apple only offer the 128GB version and not 256 or 512 Fusion drives?

    Thanks.




    • I created a DIY Fusion Drive in my Mac Pro with a 120 GB Mercury Accelsior_E2 PCIe SSD. So far the performance has been excellent. To me it appears that Apple is correct in there decision to use a 128 GB SSD for the Fusion Drive.




    • This is a good question. At this time we do not support any SSD or HDD upgrades for the 2012 through 2013 year iMacs. However if in theory you can upgrade those drives you may certainly create a Fusion drive with the steps in this article.




  • Hi there, I got up to step 10 with no issues.

    Now I can boot from my ‘clone’ drive but it doesn’t appear to have a recovery. What I am wondering is if I just ‘clone’ my clone drive onto my fusion drive, will the fusion drive still operate as a fusion drive? Will it know to put the operating system on the SSD and so on?

    Thanks




    • You have to specify the partition of your spinning drive and not the whole drive. Since your recovery is now lost, you have to undo the fusion drive, reformat to a single drive, reinstall mavericks on the spinner. This creates the recovery partition. When you make the fusion drive after all this, specify only the non-recovery partition on the spinning drive with the SSD drive. It will be something like disk1s1, not disk1s. Then copy your backup/reinstall over the fusion group and you should be good to go.




      • I ended up just going ahead and cloning the clone onto the fusion drive – and it works great! Insane speed boost, and time machine works. I think I am good to go. I may not have a recovery partion but I have my time machine backup so thats really all I need.




  • Hi, does anyone tried to run Fusion Drive on MBP early 2011 with OSX Mavericks? There were some problems on this particular model of MBP with running Fusion Drive in OSX Mountain Lion so I was wondering if the new version of OSX has this same problem or if it finally is working with this model? Thanks.




    • It works, but the SSD cannot be in the optical bay. Put the old HDD there or a compatible HDD.

      The optical bay only works with SATA2 (3Gbps) devices or slower. Just about all SSDs are SATA3.




  • I did this successfully on OS X Mavericks, however when I try installing an Application that requires the App to be installed in the root applications folder (CrashPlan), it installs it by default to Fusion Drive > SSD > Applications instead of Fusion Drive > Applications. I’ve also set the Application to install to a custom directory (the latter) but it still installed to the prior. Any ideas?




    • This is a bit confusing. If the Fusion drive was setup properly you should only have the Fusion Drive. Your SSD should not be visible within Finder. Either way I’ve done some digging and have not found any known issues of Crashplan being installed on a Fusion drive. If you continue to experience installation issues It would advised to contact the maker of Crashplan.




  • Hi, I have just completed installing two drives a Samsung 250GB SSD drive & a 1TB 7200 rpm Hitachi drive to my 2013 Mac Mini with Lion OS X 10.8.5 installed. I am a little embarrassed that even after watching your video I still had some difficulties removing the Fan & IR connectors & broke the fan connector & the IR socket on the Mac Mini’s MB. Anyway I was able to fix it by Soldering, because I know that this upgrade would have voided my warranty anyway. I know that if Steve could see inside my New Mac Mini now he would turn in his grave.

    I have tested all the hardware and it appears to be working regardless the mishap. The main reason I am writing is that now after installing the Lion OS X the installation forced me to create a new installation of Lion OS X with with a new user name, is this Norma? Also it appears that even after transferring all my data from external drive (original Mac Mini drive) I cannot access Ext Time Machine all previous date are greyed out, but if I boot from my external original drive I can access all the Time Machine Data copies. Also in the new installation of Lion OS X for some strange reason I cannot access the Right Mouse Button, but I again boot to the external original drive everything is ok.

    What would you suggest do I need to try to re-install the Lion OS X from the original Mac Mini drive because when I tried to install Lion OS X from the Clone I made using CCC , my Fusion drive refused to boot.
    Could the mouse problem be driver problems with the Fusion Drive, at the moment I at a lost for answers.
    In other respects the Fusion Drive douse seems to be working very fast as aspected.
    Please advise rgds…..Joe




    • This is super odd. I haven’t come across anything like it. The best approach would be booting from the recovery partition on the time machine drive and attempting to restore from the time machine backup that way.




  • Thanks for this great information.

    I have a carbon copy clone (mountain lion) of my drive that i was using in my macbook pro (late 2008) including all my apps that i want to keep. I dont have serials / cds handy so dont want to use migration assistant. I also dont have any files in particular that i wanted to migrate across. I use the cloud and will hand select a few files on the new install.

    I’m a bit confused by step 10; boot to your clones recovery partition. Is this just been done to enable the migration assist. Will it have this? I dont know if ive used a recovery partition before when i have copied from drive to drive using CCC.

    Can i skip 10 and simply install a fresh mountain lion install….and then using CCC to copy from the source (the clone) to the target (the fusion drive). I know this is realy ignorant….but doing this wont undo all the setup steps for the fusion drive will it – i dont think so but wanted to check.

    OR is the better way to do this…to launch up the new imac (installing mountain lion) and then use Carbon Copy Cloner to migrate my prior drive across…..update to 10.8.2….and then follow all of your steps exactly the same.

    Hope thats clear. Many thanks for your help.




    • A quick follow up to my above post….
      I have been doing more extensive reading and trying to understand what to do.

      1) I now understand that i cant simply do a full clone from CCC (Mountian Lion but previous version) because the OS is newer on the Mac Mini. I accept that I will be using Migration Assistant to get my apps and files.

      2) Regarding Step 2. My situation is that the mac mini will be brand new and the SSD and ITB drive will also be brand new (so no data to keep on them). However, I already have a bootable copy of all my apps and data (made using CCC in prior mountain lion) that i will want to later use in migration assistant to bring these files across.

      So my understanding is that i would need to clone the Mac Mini simply so that i can boot to the version of OSX that came with it. What i dont fully understand (have searched a lot on this…) is exactly how i make this clone so that it has a recovery partition (mentioned in Part 10)….

      Should i use Time Machine (or another better / easier method) to create this clone, or could i do it will Carbon Copy Clone. Whats easiest?

      I have checked CCC website and it does appear that you can add a recovery HD to a clone, but i’m just looking at the easiest option. I have tried to read up on Recovery HD’s (apple and other sites…but i dont fully understand them). I also got sidetracked reading up about the internet recovery for the OSX (seems there is more than one way to do this). Anyway…the more i seemed to read i began to get confused..so i needed to write this post ;-)

      What i intend to do (I know this is basic, but might help others who are less tech savvy and wanting to do a similiar thing)

      1) Purchase Mac Mini Late 2012, extra RAM and a 240GB SSD (done)
      2) Turn on the stock Mac Mini, updating the OS to the latest.
      3) Clone mac mini to an external drive using Time Machine
      4) Install SSD using the OWC ‘Data Doubler’ SSD/2.5″ Hard Drive installation Kit and your video (thanks) and install the new RAM
      5) Boot to the mac mini clone (step 4 in your explanation)
      6) Follow the steps in your explanation up to and including step 11
      7) For step 12. The data and apps that i want to migrate will come from another external drive (not the mac mini clone), therefore at this point “clone” for me refers to the external hard drive that was a full copy bootable CCC clone of of my prior mac – I will be using Migration assistant for this (NOT referring to the Mac Mini Clone)

      Does this seem to be the correct way to do it….or should i do a migration assistant / setup bringing over my old apps and data at step 2 (in my list above) rather than at step 7 (in my list) and then creating a Clone of this ) Would there be any difference? If i did it that way surely im wasting time putting all the data on the hard drive, then cloning it because it going to be deleted because the drive is reformatted to setup the fusion.

      I do hope that makes sense. Many thanks for your reply. Apologies for my misunderstanding in my previous post.




      • The most reliable way to configure your new Mac Mini and copy the information from your MacBook Pro to the Mac Mini will be as follows:

        1) Purchase your Mac Mini Late 2012, Extra RAM and a 240GB SSD
        2) Turn on your new Mac Mini and update to the latest OS to make sure it is properly working.
        3) Install extra RAM and make sure your Mac Mini is working with the new memory
        4) Update your MacBook Pro to the latest version of Mountain Lion (10.8.5)
        5) Perform a Time Machine backup of your MacBook Pro to an external hard drive – http://support.apple.com/kb/ht1427.
        6) Begin following our steps in this blog. When you get to Step 4 you may use your MacBook Pro’s Time Machine backup drive to boot from.




  • Hi,

    I am wondering if it is possible to create a diy fusion using the following cs commands:

    diskutil coreStorage convert

    diskutil coreStorage addDisk

    diskutil coreStorage resizeDisk

    As of Os X 10.8.4 they are available but undocumented as stated in the following web site:

    http://blog.fosketts.net/2011/08/04/mac-osx-lion-corestorage-volume-manager/

    The advantage of using these commands is that are non destructive, compared to the method given above.




    • Good question. Unfortunately we have not experimented with this type of setup ourselves.

      We do encourage the DIY mentality, so please feel free to attempt this setup and let us know how it works for you.




  • i bought your kit and created the fusion drive with the ssd and the original 500gb drive. However, now i want more space and want to upgrade the mechanical drive to 1tb or 2. Whats the easiest way to do this? Thanks




    • I would first recommend backing up your data that is on your Fusion Drive.

      Once your data is backed up, the current fusion setup will need to be deleted. Since you can’t erase the volume that you are booted into, a boot disk when need to be created to boot from. I would recommend Apple’s OS X Recovery Disk Assistant which can be created on a Flash Drive.

      After you boot into the Disk Assistant, Open Terminal and Type: diskutil cs list

      This will give you a listing showing any Core Storage Logical Volume Groups (aka Fusion drive). You will need to copy the long alphanumeric string for the Logical Volume Group that is listed

      In Terminal Type: diskutil cs delete groupString

      The Fusion should now be deleted. From here proceed to go back through the above steps to create your Fusion Drive.




  • Hi,
    I’ve done it, but know I have some issues with the recovery partition:
    - when I start the computer holding alt key, the only hard drive i can boot on is machintosh HD
    - when I start the computer holding command+R, i do have the recovery process
    - Impossible to create an usb recovery http://support.apple.com/kb/HT4718 , the program says it can’t find the recovery partition

    Can you solve it?
    Thanks,




  • Put my new OWC 3G SSD into the main drive bay so now both the spinning HDD and SSD are 3G.
    Got the same results as before. The format process hangs after I have successfully created the fusion drive.

    Any other ideas??




  • I wonder if it is possible to set up an SSD drive to run OSX and Applications while still using existing hard drive for user files?




  • Hello I have a late 2012 Mac mini, and after fitting my own ssd, I entered recovery mode and selected to fix the drives, at which point it reinstalled OS X automatically on a single logical volume created from both drives. As this is a late 2012 Mac mini, is this a proper fusion drive, or will I have to do it as per the guide? Thanks.




  • i just installed the SDD and now am getting some errors when trying to restore from time machine.

    the error says “the operation cant be completed because you don’t have permission to access some of the items. it also states: error code 8062 and 8003. it states these errors twice.

    i tried to fix by repair permissions in disk utility but to no avail.

    any ideas what might be the problem?




    • We are sorry to hear about the issues. This issue can be the results of a lot of things. If you are trying to restore from Time Machine before installing the OS, you can try installing the OS first and than using migration assistant to restore from time machine. Please contact our tech support if you continue to have issues restoring your SSD.




  • Yesterday I received my 120 GB Accelsior_E2 for my Mac Pro. I had a printed copy of your directions to create a Fusion Drive with a 1 TB drive currently in my Mac Pro.

    The installation of the Accelsior_E2 was trivially simple. Then creating the Fusion Drive afterwards with your direction was equally simple. After that came the long part of moving all my data around to utilize the Fusion Drive.

    Today I am experiencing quicker and smoother performance on my Mac Pro. This is especially noticeable with Aperture.

    Allan




  • Created my drive using this guide and the OWC kit on my i5 2012 Mac Mini last night, everything seems to have worked great. Used an intel 330 120Gb SSD and the factory 500Gb platter. Recovery install to new fusion drive then migrated data from Carbon Clone Copy backup, couldn’t have been easier.
    Hopefully it has worked, everything looks good, just have to see how it performs now (definite decrease in boot time so that’s a good sign). Bit of confusion and arguing for and against enabling TRIM, I’ll leave it for now and do some more research.
    Thanks for the guide, made the whole experience so much easier. Only trouble I had, if you want to call it that, was getting the IR connector off, it is hard to get access on the 2012 models, and I did chip a small piece off the connector, but nothing to have any effect on it, all working good now it’s back together. I can only say to others that want to do this, take your time and read the instructions more than once to reduce and confusion or uncertainty in doing this upgrade.




    • 20 second boot over about 2 minutes prior to adding the SSD and fusing the two drives. Overall seems to be running faster, hopefully I’ve done this all correctly and it’s working as a fusion drive should.




  • Hi,

    I have just created a fusion drive (that’s what I hope) in my macbook pro early 2011 (10.8.3) but I’ve just read comments saying that maybe i’ve just created a core storage…. Is there a way to check this? Has someone successfully created a Fusion Drive in a MBP?

    Thank you!




      • Thank you for the article! What’s the difference between the two methods apart from upgrading to 10.8.3? I followed the steps in this article and I think I’ve been lucky because they seem the same to me. Thank you for your answers!




    • Hi,
      I just tried to start FusionDrive last night, I tried almost everything, but all atempts failed. According discussions on macrumors and other forum there is some problems with MBP early 2011. As you mentioned, you created FusionDrive succesfully. May I ask you, what is your configuration? What types of discs you used? My setup is SSD Intel 520 240GB (SATA3) and HDD Seagate 1TB (SATA2). I’m curious about your SATA port types and also where is your SSD placed (in optibay or in default drive bay?), because my guess is that the problem is somehow related to SATA port i MBP early 2011. So I’m ready to change one of the drive to be both drives on the same SATA version, but not sure which one of the drive is the culprit. I’d rather change the HDD for SATA3 drive, but not sure if the drive with SATA3 will be working flawlessly in optibay.
      Thanks for your answers.




      • I suspect that the issues isn’t in creating a Fusion Drive itself, but rather has to do with the type of drive being used in the optical bay on those machines.
        Simply put, the optical bays of the 15″ and 17″ models are too unstable for 6Gb/s drive use and a 3Gb/s drive like our Mercury Electra 3G SSD or a 2.5″ SATA HDD specifically listed as 3.0Gb/s should be used.




        • My laptop is a macbook pro 13″ from early 2011. The configuration is as follows:

          128 gb SSD Crucial M4 (Sata 3) placed on the default Sata 3 drive
          500 gb genuine toshiba HDD installed on the Sata 2 optibay

          I hope this information is useful.

          Gerard




        • I have the same problem as above, 2011 MBP 8,2 with a new OWC 6G SSD in the main drive bay and a new 3G 750GB HDD in the diskdoubler (optical drive).

          In terminal I get to point of formatting the fusion drive and it hangs. I am on my second HDD with the same results.
          Do you have any other people saying that dropping down to a 3G SSD will solve this problem? I threw away my OWC SSD package so I’d just have to buy another one :( so I’d like to be sure before dropping the bucks on it.

          As a side note, I read about a firmware update back in 2011 to fix the 6G support for these laptops. Am I correct in presuming that when I use the most recent 10.8.3 installer, I do not have to worry about that? This computer has had 10.8.3 installed on it in the past.

          Thanks!




          • You should double-check that the firmware update you’re running is the current version MBP81.0047.B27 (EFI 2.7).
            If not, perform that update – instructions in the link above.

            Then under System Report > Hardware > Serial-ATA check that the Link Speed and Negotiated Link Speed on each channel is correct for the drives installed.
            For the SSD it should be:
            Link Speed: 6 Gigabit
            Negotiated Link Speed: 6 Gigabit
            And the HDD in Data Doubler:
            Link Speed: 6 Gigabit
            Negotiated Link Speed: 3 Gigabit

            With the firmware updated, there should be no issues with using an OWC 6G SSD in the main bay.




            • The firmware was a little behind so I updated both EFI and SMC to their current versions.

              My dual-spinning 3G fusion drive system was still working fine after the update. The system report showed:
              Link speed: 6
              Negotiated Link speed: 3
              which would be expected I guess since both drives were 3G.

              So I swapped back in the 6G SSC into the main drive bay, and am right back to having the same problem.

              The LV never completes in Terminal. If I look in Disk Utility, I can see my fusion drive and the LV, but the LV is grayed out and I cannot do anything with it. It tells me the volume is locked.

              Back in terminal, I feel like I’ve tried all I know, converting, unlocking, even deleting the LV and all commands for the UUID of the partition on the fusion volume error out.

              My 3G OWC SSD should arrive this afternoon. I will report back.




            • I received my 3G OWC SSD and installed it in the main drive bay with my 3G spinning HHD in the optical bay.
              Went through the process and it stalled out in exactly the same way, the fusion drive gets created but it will not take the formatting.

              The volume looks like it is formatted but it is locked in Disk Utility.
              Once it is “half-created” you can no longer do anything with it in Terminal e.g. delete it or reformat it.

              Any other ideas? I’m about to give up on this one.




              • You can Free Space the drives to start the process over.

                “Free space” is an option for formatting the drive in Disk Utility:

                1. Choose the drive you’re looking to “free space.”
                2. Under the Partition Tab choose Volume Scheme – 1 Partition
                2. For “Options…” choose “Master Boot Record”
                3. The for “Format:” Choose “Free Space”