Coupling Apple HDD and SSD: Create Fusion Drive yourself (step by step instructions with pictures)

Apple Fusion Drive - HDD and SSD hard drive combined

The benefits of Apple Fusion Drivewith which combine an HDD and an SSD to achieve faster read and write values, you can find here. At the end of the article, instructions were also announced to give you a guide Create Fusion Drive yourself can. This will now be delivered later; delayed, but at least;) I scooped through some sources to prevent possible false reports, and also found a video whose screenshots I use as images. I will also include the video (in English) in its entirety at the end of the post.

Update 19.11.2017/XNUMX/XNUMX: Procedure under macOS High Sierra

A reader asked me today how he should do that with the FusionDrive in detail and whether the Mac automatically recognizes them after installing the two disks and creates a Fusion Drive. Unfortunately - or fortunately - it doesn't, because you can decide for yourself what to do with a new hard drive.

For me, however, the email was reason enough to look again whether something else has happened in the Fusion Drive area with High Sierra, or whether only APFS was the novelty of the hour (at least with regard to the disk utility). The short version is: To create a Fusion Drive you still need the help of the terminal. I checked through the utility and selected two hard drives that could have been "merged", but there is simply no option for it. So you still have to use the terminal, as described below, to create a Fusion Drive yourself.

For everyone interested, here is the short version of how to proceed, for example if you want to replace the internal hard drives with larger ones and then let the two new ones run as a fusion drive:

  1. Backup of the entire data as a clone (e.g. with a Backup software like Super Duper or Carbon Copy Cloner) to an external hard drive
  2. install the new hard drives
  3. boot the Mac from the external backup disk
  4. "Connect" the new internal hard drives to the FusionDrive using the instructions above and the terminal
  5. Copy all data from the external backup disk to the FusionDrive with Super Duper
  6. Shut down your Mac and unplug the external hard drive
  7. Restart Mac; it would then have to boot from the new FusionDrive if everything went smoothly

I always recommend a 1: 1 backup with Super Duper or Carbon Copy Cloner to do, because TimeMachine also said before that my backup would be useless. If I hadn't had a 1: 1 backup on another hard drive at that moment, all my data would have been gone. So it is better to buy an external USB hard drive (2,5 inch) and make one backup too many than one too few.

Preview: Preparing to Create the Fusion Drive

You can already find some previews in the article linked above. Here I just want to give two more tips that are important before you start creating a Fusion Drive:

  • The external SSD disks should be connected to the fastest possible connection (USB 3.0; USB 3.1; Lightning or FireWire - depending on the Mac model)
  • Make a backup on an external hard drive beforehand, (about one with time Machine, and a 100% clone with a program like Super Duper or Carbon Copy Cloner) since the first step in merging the disks is cleaning them up

After executing the commands listed below, it is also necessary to reinstall the operating system. You can easily do this using the utilities (cmd + R) that you have to go into anyway to create the Fusion Drive. If in doubt, you should have a boot USB stick on hand. I have also described how to create it in the form of instructions: click here.

Create Fusion Drive yourself: step by step instructions

Now let's get to the heart of the matter and create a so-called one from a rotating disk and a flash drive Fusion Drive with coupled storage and intelligent data and program management. To do this, a backup is first made, as highlighted above, and then the Mac is restarted.

Step 1: Start the Mac and hold down 'cmd' + 'R' while booting

The heading says almost everything: So you restart the Mac or switch it on first. When booting the operating system, hold down the Command key and the R key at the same time. Depending on the system and age of the Mac, it can then take a while for the Apple logo to appear. If the Apple logo appears, you can release the buttons again. Then you will be shown some of the system's utilities in a window.

Create Fusion Drive yourself, program it yourself Terminal Mac Utility Instructions

Image source: YouTube / Version3tech

Step 2: Further procedure in the terminal

Mac OS cmd R Open Utilities Terminal

Image: Sir-Apfelot.de

We do not need the utilities displayed in the window, but work with the Port further. You should be able to open this via the menu bar of the “Utilities” menu (upper edge of the screen). Take a little time for the following steps, because now it's down to the nitty-gritty, programming commands and thus also the correct spelling! Ready? Let's go.

Step 3: Create Fusion Drive yourself, instructions with pictures

In the terminal you give first disktil list a. This will ensure that an overview of your hard drives is generated and displayed. Depending on whether and how you have created virtual drives, the corresponding number will be listed. The two real plates are of course most important for the following steps. If in doubt, look for the largest values ​​for "SIZE" at the top of the list, ie 128 GB, 500 GB, 1 TB, etc. - depending on the Mac model.

Mac HDD SSD Fusion Drive create yourself generate commands code

Image source: YouTube / Version3tech

From the overview you can see the names of the records, which you can find in the "IDETIFIER" column: logically, these are mostly disk0 and disk1. But if you are installing and removing disks multiple times, plugging in and uncoupling and creating virtual partitions, it can be different. In the standard case, however, it is as described; Especially the HDD is easy to find because it is standard Macintosh HD heißt.

Fusion Drive hard drives names Fusiondrive disk0 disk1

Image source: YouTube / Version3tech

So you now have the names of the two plates - that takes you to the last line of the overview, where –Bash-3.2 # should stand. There you now enter another command. This is discuss coreStorage create Name / dev / disk0 / dev / disk1. The name, simply called "Name" in the example code, is assigned by you individually. In the example video (see below) “Macintosh” is assigned. After entering the command, you will start it - the plates will then be deleted.

Fusion Drive Code copy alphanumeric character string

Image source: YouTube / Version3tech

In the picture above you can see the various steps of your command. You will get an alphanumeric code in two lines (Discovered new Logical Colume Group, and Core Storage LVG UUID:) Mark this combination of characters and copy it to the clipboard. We'll need it again in a moment.

In the next command, which is: discuss the coreStorage createVolume UUID jhfs + "Name"100% . Two comments on this: Instead of UUID, you insert the alphanumeric code. Instead of Name (yes, it is written in the quotation marks) you choose your Fusion Drive name, again "Macintosh HD" or something like that. To illustrate the whole thing again, here is a picture:

Mac hard drives Fusion Drive create your own code commands overview step by step with pictures

Image source: YouTube / Version3tech

And basically you're through now. You return to the utilities window and reinstall the operating system (second item in the list). If that is done, you can now use the merged storage medium to store programs and data.

Fusion Drive overview of combined hard drive in the Mac

Image source: YouTube / Version3tech

Divide the value by 1.000 or enter 100%? This is what other instructions say ...

Of course, I not only used the video in question as research material, but also other instructions. Some of these are very deformed and therefore complicated. In addition, it is not uncommon for them to state that one should calculate a value of the memory capacity with this and that formula in order to then insert it into the last command. I find that too difficult if you want to use both platters 100 percent as a Fusion Drive. Hence the alternative given above with the value 100%. You don't have to make it harder than it actually is;)

Once again, all steps of the Fusion Drive generation in short form

  • Start Mac and hold down cmd + R until the apple appears
  • Start the terminal from the utilities
  • disktil list
  • Find the names of the hard drives
  • discuss coreStorage create Name / dev / disk0 /dev/disk1
  • discuss the coreStorage createVolume UUID jhfs + "Name"100%
  • Install OS X or macOS
  • Ready

How To Fusion Drive: YouTube Disk Fusion Tutorial

Questions, Answers and Views

I hope this guide was understandable and effective. If you have any questions or something is unclear: then write a comment. I would also like to hear from you if everything goes well and this Step by step instructions for creating the Fusion Drive was successful! During my research I also noticed one more thing: In the worst-case scenario, I still need instructions on how to dissolve the merger - I'll write them in the next few days;)

 

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53 comments

  1. Jens says:

    Thank you for the simple help. Now I also have a self-made fusion drive

    • sir appleot says:

      Hello, Jens! But of course! And don't forget: make backups ... with the Fusiondrive only one disk of the two has to break and all data is over!

  2. Andreas says:

    Before I venture into setting up a FusionDrive, here's a question:

    I installed an SSD and installed the MacintoshHD in place of the SuperDrive. I transferred all data to the SSD via Carbon Copy Cloner. I also backed up the MacintoshHD to an external HDD via TimeMachine.

    If I go here now and have to replay the system because the HDD and SSD have been erased, I don't know how to get macOS Sierra onto my hard drives.

    What steps do I have to take to reinstall the system?

    Maybe the question is completely childish ...

    • sir appleot says:

      Hi Andreas!

      The question is definitely not childish. :)
      I haven't tried the procedure myself yet because I have everything on the internal SSD myself and don't use a Fusion Drive.
      But I think this is how you do it:

      - Start the Mac from the external backup
      - Then start the disk utility and connect and format the two disks to the Fusion Drive
      - Then copy the data from the backup to the Fusion Drive with Carbon Copy Cloner and start from this disk
      - after copying you have automatically reinstalled Sierra on the Fusion Drive

      All pure theory. :)
      But it should work!

      Greetings!

      Jens

  3. Jurgen F. says:

    Great instructions, I also went through the whole thing with Apple Support over the phone after I accidentally deleted something. Now to my question: I have a Fusion Drive again (supposedly) - can I somehow check that? I also use Windows 10 via Bootcamp. Windows runs very, very slowly even though everything is installed correctly. Does it make sense to dissolve the Fusiondrive, use the SSD separately and install Windows 10 on it (is that even possible?)? Thank you for your answers. LG

    • sir appleot says:

      Hi Jürgen! Sorry, I'll be a little later on the holiday. : D But to your questions:

      1. If you open the disk utility and click on Fusiondrive, the information should say that there is a FusionDrive.

      2. Slow Windows 10 via Bootcamp: I have no experience with it, as I only use Windows 7 on Parallels, but if it is slower than it "should be technically", it could be due to a full hard disk. If your Bootcamp partition is full to the brim, Windows (like any other system) will skid. If it isn't, the problem could be low RAM. I think the Mac should already have 16 GB of RAM so that Windows runs reasonably smoothly on it.

      3. Windows on SSD: Yes, that's basically possible. You copy all data from the Fusion Drive to another (external) hard drive. The best way to do this is by Carbon Copy Cloner or Super Duper. Then you format the individual hard drives (SSD and HDD) and install your boot camp with Windows 10 on the SSD. However, your macOS then runs on the "normal" hard drive, which of course makes it quite slow. From my point of view, the best solution would be to get an external hard drive enclosure with SSD (e.g. this one from Samsung) and then install Bootcamp with Windows. Then every system is on an SSD and has plenty of space. If it is then slow, it should be due to the RAM, which can also be upgraded. If it's an iMac, I have here is the appropriate article to you.

  4. Thomas says:

    Thanks for the guide, am considering trying it.
    In the network, however, you read everywhere that you should definitely use Thunderbolt, I'm now a bit unsettled.
    And if Thunderbolt, does it make a difference whether you use a Thunderbolt cable or a miniDisplayport cable?
    There are enormous differences in price.
    Vg

    • sir appleot says:

      Hello Thomas! USB 3 wasn't much slower in the practical test than Thunderbolt 1. It looks different with Thunderbolt 3, but to be honest, that doesn't make a big difference. Even with USB 3, a Fusiondrive is so much faster than a normal rotating disk that I would definitely do it. And yes, you have to use a Thunderbolt cable. Mini DP cables look the same, but the insides are different and they don't support Thunderbolt. So your hard drive would not be recognized. Another important note from my side: Since a Fusion Drive statistically has a higher chance of data loss due to the total failure of one disk due to the two disks, we would definitely make backups on a regular basis. I use the online backup service for this Backblazewhich is very well geared towards Mac users.

  5. Magguz says:

    Hello Thomas,

    I have an iMac 5k from 2015 and I am very unhappy with the built-in 1 TB Fusiondrive.
    The box is significantly slower than my 2013 model, to which I had connected an external SSD via Thunderbolt.
    Do you think you could possibly. get a speed gain here with the external solution?

    Thank you for your answer and have a sunny week

    Magguz

    • sir appleot says:

      Hello Magguz! I do think that a pure SSD should be even faster externally. You also have Thunderbolt on the 2015 iMac, so you're even faster here than I am with my old Firewire on the old iMac. If you still have the SSD somewhere, give it a try. You can use Carbon Copy Cloner (Link) make a 1: 1 copy of the disk on the SSD and then boot before the external one. Then you have a direct comparison. ;)

  6. Magguz says:

    I'll test that right away, thank you very much for the tip!

    Do you know whether the copy of the cloner can still be used after the trial period has expired, or do you have to buy the full version?

    • sir appleot says:

      The copies are ALWAYS usable and not tied to a license. Even if you uninstall the program, the copies will of course still work. Anything else would be grossly nasty and not very user-friendly. More like mafia methods. ;-) Alternatively, you can also "Super duper!"for the Mac. It's completely free - permanently.

  7. Kidney says:

    Great guide. Is it imperative to create a Fusion Drive? I have just installed an SSD in the MacBook Pro and now want to remove the drive and install an HD instead. Can't I just tell the system the path to the HD for its data?
    I'm looking forward to an answer. best regards

    • sir appleot says:

      Hello Rene! The Fusion Drive is of course not compulsory. It is the "comfortable" solution if you only have a small SSD on which not everything fits. Of course, you can also outsource certain things such as the photo library or the like, but it makes sense if the startup volume with the macOS is on the SSD.

      I didn't quite understand why you want to remove the SSD from your MacBook Pro and replace it with a rotating hard drive. That's exactly what everyone else is doing the other way around: HD out and SSD in the MacBook. : D What are the advantages of the internal HD and the external SSD for you?!?
      LG! Jens

  8. Kidney says:

    Hey Jens, thank you for your nice message. Sorry, I got it wrong. So I want to swap my DVD drive for an HDD. A 500 gig SSD is currently installed. As you have already correctly stated, I would like to outsource data such as the photo library to the HDD. But now I'm not sure whether I'll set up a Fusion Drive or some other option, if possible. What would you recommend? Will the Fusion Drive brake my SDD?

    • sir appleot says:

      Hello Rene! Ah, now I get it. : D To your question: Yes, the Fusion Drive is slower than a pure SSD. For this reason, I would rather try to keep a pure SSD and an HDD with your SSD size and then install the macOS with programs on the SSD and move folders that are used less often and take up a lot of space to the HDD. You could use the Daisy Disk program to see which large folders are lying around on your disk that you can swap out. The photo library and iTunes have already made a big difference to me. Then you definitely have the fastest solution.
      In any case, it would be important to make a backup regularly, because SSDs can withstand fewer read-write accesses than normal hard disks. And the way data is stored on the SSD makes it much harder to recover data from an SSD. At least that's how I read it once ...

  9. Andi says:

    Hello Jens, some time ago I created a Fusion Drive following the instructions above. Now, when I start the computer, I first see the crossed-out circle ("prohibition sign") before the apple logo appears and the computer starts up after various waiting times. In addition, I often notice miserably long loading times with the rainbow cursor. Do you know something like that? My computer: Mac Mini (late 2012), macOS Sierra, 16GB RAM. Thanks in advance ... Regards Andi

    • sir appleot says:

      Hello Andi! So the prohibition sign is the indication that the Mac cannot start from the selected startup disk. He tries it first, then shows the prohibition sign and then tries the next available partition with an operating system. I assume you have a hard drive set as the startup volume that no longer exists. Just have a look under System Settings -> Startup Disk and select your Fusion Drive there. Then it should work out.

      I can hardly say why the loading times are long and why the colorful beach ball is coming. Does that happen with certain programs? You can start Spotlight (CMD key and space bar) and then enter "Activity Monitor" and start the program. There you can see in the CPU tab when a program is generating 100% or more CPU load, for example, or under "Memory" when your main memory is full and it has to transfer data to the hard drive. This also often paralyzes the Mac. Maybe that will give you new knowledge. I'm curious about them!

  10. Markus sound says:

    Moin,

    Thank you for the good manual that I just used for my iMac 5k. There I replaced the internal HD with a Samsung EVO850 1TB SSD. Since I have the iMac 5K late 2014 with 128GB of internal flash memory from the original Fusion Drive, I now have a Fusion Drive with two SSDs.

    BlackMagic Disk Speed ​​states for Apple Flash memory: 720MB / s read, 620MB / s write. Samsung EVO850: 500MB / s read, 480MB / s write.

    With Fusion Drive from the two SSDs, BlackMagic Disk Speed ​​reports the values ​​of the Samsung SSD, i.e. 500MB / s read, 480MB / s write. I don't know if and to what extent I can still benefit from the somewhat faster Apple storage with the Fusion Drive, but I find having a 1,12TB partition alone more pleasant than running the Apple storage separately.

    Time Machine is, in my opinion, a must with Fusion Drive. And it makes resetting a lot easier. Boot the recovery partition, do whatever you want with drives, restore from TM backup, connect to NAS, wait 3 hours, done :-)

    • sir appleot says:

      Hi Markus! Thank you for your experience building the Fusion Drive. It is actually not intended for two SSDs, but of course you can also "fuse" two SSDs to one disk. : D
      You're right: TimeMachine is definitely a must for a Fusion Drive. I would even go so far that I would make a 1: 1 backup of the FusionDrive to a large, external hard drive every now and then. This is then also bootable ... ... and I've heard from time to time from people where the TimeMachine Backup has failed for whatever reason. Although it always went through cleanly when creating.
      Oh, maybe a comment about your speed measurements: Often it is not the high data throughput that feels "fast" when working with a Mac, but rather the fast access time. For example, if the Mac has to read a lot of small files when it boots, MB per second is less important than fast access time. For this reason I would not worry if your FusionDrive "only" manages about 500 MB / s.
      Greetings!
      Jens

  11. Florian says:

    Hallo,

    Very nice instructions, thank you.

    I had two questions:

    1. Can I format the Fusiondrive with APFS on MacOS High Sierra?

    2. How does the Mac know which storage is faster? Just in the order when I enter / dev / disk0 (fast ssd) in the command before / dev / disk1? Or does it recognize that automatically?

    LG Florian

    • sir appleot says:

      Hello!
      To your questions:
      1. Yes, since the last update, APFS also works with Fusion Drives.
      2. Over time, the Mac "learns" which files are used often and then packs them onto the SSD part of the Fusion Drive. That is why it takes a few days for a Fusion Drive to "sort itself out". But that works automatically. You don't have to do anything. If you are wondering whether the Mac recognizes whether it is working with an HDD or an SSD: Yes, if you look at an HDD and an SSD in the disk utility, the Mac can also tell you which is an SSD and which is an HDD. The order in which the Fusion Drive is created is irrelevant.
      VG! Jens

      • Florian says:

        Many thanks for the answer.

        Ah ok - in this case the tiny 30GB Apple SSD should be combined with the Samsung SATA SSD.

        Do I enter this from the command?
        discussil coreStorage createVolume UUID apfs "Name" 100%?

        • sir appleot says:

          Hello Florian!
          Yes, this should be the "logical" extension of the command if you want to create an APFS Fusion Drive. I haven't tried it myself because I have a 1 TB SSD in the MacBook Pro and not a Fusion Drive. So I can't say for sure whether that will work. But maybe you can test it out and let me know if the syntax is as correct as you suggested.

          • Florian says:

            Hallo,

            Until a few days ago I still had the FusionDrive, consisting of the NVMe SSD from Apple (30GB) and a SATA SSD, in operation.
            The whole thing with HFS +.

            Result: The system ran so far stable (macOS 10.13) and faster than alone on the SATA SSD. You can only feel the whole thing during the boot process, which is a little shorter. Otherwise it is only noticeable in benchmarks, which reach 859MB / s when writing and 1360MB / s when reading.

            The main advantage is that the 30GB SSD can also be used sensibly, because a boot partition on a JBOD is still not possible. Also, the Bootcamp Assistant persistently refuses to carry out the installation with two built-in SSDs, so that either the NVMe SSD for Windows remains (a bit too small) or a lot of stress with the EFI partition on the SATA SSD.

            Windows 10 via Bootcamp was installed on the FusionDrive on the slower SSD part (SATA SSD) and achieved the expected values ​​of around 500MB / s.

            MacOS seems to correctly recognize which is the faster SSD and also uses the 4GB cache successfully.

            Error in the test period: The system had to be set up again after a while because no more files could be deleted. I suspect that this is more of a problem in relation to TRIM. This was enforced by trimforce. Without it the whole thing went later without any problems.

            APFS: From MacOS 10.14 (Mojave Beta), the Mac automatically converts the FusionDrive formatted with HFS + according to the above instructions to APFS during a new installation. So far everything works with almost the same speed without any problems.
            However, if you don't want to convert your FD to APFS, you only have to install it via the terminal with the appropriate parameters.

            I forced TRIM again and will continue to watch the whole thing. Bootcamp partitions the FD correctly with APFS right from the start.

          • sir appleot says:

            Hello Florian! Thank you for your interesting insights. I've only run Windows on Bootcamp once. But since you have to reboot again and again to use Windows or macOS, it became too tedious for me. I have had Windows running in my Parallels Desktop ever since. But how Bootcamp works with a Fusion Drive - or not - was not yet clear to me! I wish you that the current solution with APFS runs smoothly for you in the long term!

  12. Benjamin says:

    First of all, thanks for the well-written instructions!
    I have a couple of questions because I ran into a couple of problems: In my MacBook Pro (2011), the installation went smoothly overall, I made the SSD and HDD into a FusionDrive and everything is still running. Only I noticed that the fan on the MacBook Pro goes on practically immediately, no matter how small it is used. Is that due to the two hard drives? And is that even necessary? They won't produce that much heat, will they? Is it possible to adjust the fan again?
    My other question is about installing it in my father's MacBook Pro (mid-2012), which I haven't had any success with. Meanwhile the MacBook doesn't even start from the original HDD, my guess is a broken HDD cable. Has anyone else had experience with that?
    Is it also possible to only use the drive bay (with the SSD) and leave the HDD space completely free? Would save weight and maybe not cause any problems with the cable. But if you want to install SSD and HDD now, is it relevant in which place you put which hard drive? Or can you put the SSD in the drive space as well as in the original HDD space?

    • sir appleot says:

      Hello Benjamin!
      The first question about the fans: Have a look SSD fan control. This allows you to control the fans somewhat. I suppose it's because there is a sensor floating around inside that was previously attached to the drive. This may deliver incorrect values ​​and then the fans start up.
      Because of the second question with the HDD and the SSD: Unfortunately, I have no experience because I have not yet done such a conversion. But from understanding it could be a broken cable. Or the Mac is looking for a startup disk and cannot find one. If you were to install the system on the SSD (works with another Mac too), then you could plug in the SSD and boot from there. However, I would then install over it again so that the macOS is optimized for your computer.
      Because of the two drive bays: You don't have to use both. A shaft can also remain empty ... that's no problem.
      VG! Jens

      • Benjamin says:

        Thank you for your prompt reply! Thanks for the link to the SSD Fan Control, I hadn't seen that before. I installed it right away and at the moment it seems to be better, although I don't get a "Smart" option for the "Optical Drive", where the loud fan was located.
        Because of the HDD cable: It must actually be a cable problem, because on another Mac it can be booted from the SSD, but not from the MacBook in question. I ordered a new cable and will report whether that will help.

  13. Marius says:

    Thank you for the instructions,
    Unfortunately, I get the error message in the terminal: couldn`t unmount disk0
    Do you know how I can fix this error?
    LG
    Marius

    • sir appleot says:

      Hello Marius! On the Apple Support page (here the link) there is the following tip for the error:

      discussil cs create Macintosh \ HD disk0 disk1

      If you get a "Couldn't unmount disk" error, enter discussil unmountDisk identifier one, using the first previously found identifier to replace the text identifier use. Then enter the same command with the second identification.

      I hope this helps you!

  14. Marko says:

    Hi Jens,
    I am still a little unclear how I will install the MacOS High Sierra after creating the Fusion Drive, which is the last version that my iMac will support in mid-2011. I suspect that at point 2 "Reinstall OS X" the computer tries to pull the current version Mojave. According to your advice, in addition to the Time Machine Backup, I also created a clone with Super Duper on an external disk and a bootable USB stick with High Sierra installation.
    thank you for your tips,
    LG
    Marko

    • sir appleot says:

      Hello Marko! In fact, you've already got it right. You are now booting from the Super Duper backup on your external hard drive and then using Super Duper to copy everything from the external hard drive back to the Fusion Drive. Then go to System Preferences> Startup Disk and set the Fusion Drive again and restart the Mac. Then everything should actually work! LG! Jens

  15. Thomas says:

    Hello and thank you for your guidance. Well, I'm completely new to the Apple and I am the proud owner of an iMac 27 inch Mid 2011, High Sierra, 16 GB Ram, a 256 GB SSD and a 2 TB HDD.
    My question now: Can I also use Fusion Drive with my iMac specified above?
    And, do I have any advantages from it?
    Thank you very much for your effort
    Greetings Thomas

    • sir appleot says:

      Hello Thomas! Yes, you can do that in principle, but in your case I would honestly make the SSD the startup volume and install the system on it and lay out larger things on the 2 TB hard drive. A pure SSD as a startup volume is always faster than a Fusion Drive. But a Fusion Drive is still faster than a normal hard drive with rotating parts. The "disadvantage" of the Fusion Drive, however, is that the failure of one of the two hard drives alone leads to a complete loss of data. So basically double the risk. But since you should always work with backups anyway, that wouldn't be an obstacle ...

  16. Martin says:

    Hello everyone, I think the instructions are very well written. Unfortunately, I have the problem, my Mac only shows me a hard drive with 128GB, underneath is flash memory. That should actually be the SSD, but I miss the 3TB HDD. I've already tried everything, but I don't get the record displayed anymore ... can you help me?

    • sir appleot says:

      Hello Martin! Do you see the hard drive in the disk utility? And did you have a Fusion Drive? Or is the hard drive new? If so, then maybe it just needs to be reformatted to show up in the Finder.

  17. Martin says:

    Hello Sir Apfelot, the hard drive is not displayed in the FDP either. I bought the Mac in 2014 and it actually has a 3 TB FusionDrive. I have already formatted and reinstalled a hundred times, but I only see an internal hard drive with 128 GB in the terminal. Either the HDD was smoked or I somehow wrecked it in the terminal ... ?!
    Thank you in advance for your help;)

    • sir appleot says:

      No, Don `t worry. I think it is not technically possible to use the terminal to manipulate a hard drive in such a way that it is no longer recognized. I assume that either a cable has become loose or the large 3 TB hard drive has a technical flaw that cannot be straightened out with the software. List the Apple hardware test this hard drive? Or does he not even check them?

  18. Martin says:

    I have now carried out the diagnosis and the result is: No problems found. Reference code ADP000 I can't see whether and which hard disk has been checked ... ???????? ‍♂️

    • sir appleot says:

      OK, too bad. Somehow I don't know what to do next. I think a visit to an Apple service partner would be advisable here. If hard drives can no longer be seen in the bar even in the Disk Utility, something is wrong. :(
      I guess the hardware test did not "see" the disk either and therefore no error is displayed.

  19. Heiko says:

    Moin ... I found your instructions, but haven't used them yet. I have a question or two about it beforehand :)
    I have a 32gb ssd and ne 1tb disk available. as far as everything is not a problem with regard to the instructions, it should work without any problems. theoretically ... but I have a 1,1 / 2,1 and have el capitan running, with a modified boot efi. if i want to set it up again, i use a dmg, which i restore on the target drive and start with the personalization. is that the same then? set the case: copy to external, booted lion and fusion as target (lion on # (shaft) 1 and fusion on # 2 + # 3. # 4 would be linux) the fusion drive still works when I switch to # 1 + # 2?
    then another idea, maybe stupid. you can do a raid with several records. would it work to use the raid, for example consisting of 3x 1tb plates, as a counterpart to the ssd? theoretically i think so, but how does it work in practice and with the speed?

    • sir appleot says:

      Hello Heiko! Sorry, these are all questions that I unfortunately have no experience with. Neither have I ever done anything with a modified EFI, nor a FusionDrive with a raid. But I was able to read in a US forum that someone built a Raid 0 with two WD hard drives and then connected it to an SSD to create a Fusion Drive. So actually that should work. Unfortunately, I cannot say anything about the rest. :-(

  20. Denis says:

    Hello!
    I have an iMac 2019 21,5 inches 4K with a 1TB FD. 800 GB are occupied. So it's getting tight.
    My idea: buy an external Thunderbolt SSD with 256 or 500 GB, connect it and integrate it into Fusion Drive. Is the? Internal HDD + internal 32 GB SSD (current Fusion Drive) + new SSD, so three hard drives in ONE Fusion Drive System?
    Denis

  21. Jan says:

    Hi, thanks for the introduction, has been very reliable for many years. Now the system would like to dismantle for sale. What is the best way to do this?
    An SSD via Thundbolt is attached to my iMac.

    Greetings Jan

  22. Jens says:

    Finally a page without copied nonsense. Your tips helped me in concrete terms, thank you very much!

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