What about the FUSION Drives?

Discussion in 'macOS Mojave (10.14)' started by Elembytes, Jun 4, 2018.

  1. Elembytes macrumors newbie

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    Jan 20, 2018
    #1
    A few days ago it was talked that this newest MAC OS would finally be compatible with FUSION Drive iMac's. Mine is a Late 2013 and I have still been waiting for the files storage system to finally be worked out to work with the FUSION DRIVE iMACS.

    NO where in today's releases etc., is there any mention of Fusion Drives being covered in Mojave! What gives with this?

    Am I going to have to upgrade my iMac again? Sheesh!
     
  2. Cougarcat macrumors 604

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    Sep 19, 2003
    #2
    Yep, APFS supports fusion drives now in 10.14
     
  3. macvinc6 macrumors newbie

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    Aug 2, 2011
    #3
    I have an iMac 2017 with 32GB internal SSD. Can i make a fusion drive with an external Thunderbolt SSD?
     
  4. SoYoung macrumors 6502a

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    Jul 3, 2015
    #4
    Is APFS really faster on fusion drives? And is Time machine finally works with this format? I don't know if I'll jump to this format yet when I'll update this fall...
     
  5. Steve121178 macrumors 601

    Steve121178

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    #5
    I've been backing up my MacBook Pro that's formatted with the APFS file system to Time Machine since High Sierra was released...
     
  6. SoYoung macrumors 6502a

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    #6
    Oh ok thanks. I thought it didn’t work with the new file system.

    But, if the new macOS gives me issues, is it possible to go back with a previous back up with the ancient drive format without too much problem?
     
  7. stooovie macrumors 6502a

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    #7
    No, it's slower. Even on SSDs. It does a lot more stuff in the background. Don't go for APFS when raw speed is your priority.
     
  8. EugW macrumors 603

    EugW

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    #8
    Just boot off the Thunderbolt SSD. Leave your Fusion drive for data.
     
  9. bookemdano macrumors 65816

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    Jul 29, 2011
    #9
    Just to add a point of clarification, it's no problem to back up APFS volumes via Time Machine. But volumes used to store Time Machine backups must be formatted HFS+ (not APFS). I'm not sure if that has changed with Mojave, but I sort of doubt it.
     
  10. DennisdeWit macrumors 6502

    DennisdeWit

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    #10
    I have just updated from High Sierra (HFS+) to Mojave, that automatically converts the partition to APFS. I have a 2TB Fusion Drive. It took me around an hour of waiting time. Then everything booted nicely and none of my documents are gone. Everything is where it should be.

    So it seems upgrading to Mojave with a Fusion Drive will work from now on! :)
     
  11. Cryates macrumors 68020

    Cryates

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    #11
    Craig literally mentioned it onstage.
     
  12. DotCom2 macrumors 68040

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    #12
    What is the advantage of this APFS? And more importantly, disadvantages?
     
  13. SoYoung macrumors 6502a

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    Jul 3, 2015
    #13
    Wait..what? So you have no choice to convert to APFS?
     
  14. haydn! macrumors 6502a

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    #14
    Did you watch the keynote?
     

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  15. bplein macrumors 6502a

    bplein

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    #15
    A Fusion Drive is really just a logical volume on a logical volume group, which are joined together by Core Storage (CS) (underlying storage logical volume manager or LVM available in macOS). What this means is that you can group any number and type of physical drives into a group (logical volume group) and from those carve out "drives" which are really just logical volumes taken from that group.

    When CS sees that there is one SSD and one HDD in that group, it prioritizes writes to the SSD (as well as leaving often-used data there). That's it... it's a special use case of the Core Storage LVM. When you go through the steps of creating a DIY Fusion-Drive, you are really just creating a CS logical volume, and CS sees that it's one SSD and one HDD and sets up this write priority.

    So, what does this all mean? When you drop in 2 SSDs, it's really not a Fusion Drive, it's just a concatenation of the two drives, as you don't have 2 different classes of storage (SSD and HDD)
     
  16. Elembytes thread starter macrumors newbie

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    Jan 20, 2018
    #16
    No, I didn't have time to do so but have been reading Mac Rumors and that is where I had heard that Mojave would be compatible now with "Fusion" drives. However, no where post the event did I read that information. Thank you for your time and clarification in that it will. I will excitedly now await the opportunity to upgrade finally from Yosemite to Mojave. Thank you for your help!
     
  17. bplein macrumors 6502a

    bplein

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    #17
    High Sierra is compatible with Fusion Drives. I have multiple Mac minis running High Sierra with Fusion Drive. The difference with Mojave is that APFS is going to be compatible with Fusion Drives.

    You can start with a Fusion Drive on High Sierra today and migrate to Mojave at a later date.
     
  18. macvinc6 macrumors newbie

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    Aug 2, 2011
    #18
    ok, thank you for explanation.

    My idea behind is, not to open the iMac and use the high performance from the internal 32gb SSD for the core system.
    So just programs and data should be on the external thunderbolt SSD.
    Will it work out?
     
  19. bplein macrumors 6502a

    bplein

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    #19
    Your challenge is that the 32GB will be small for the OS.

    Here's a suggestion:
    1. Use an external SSD for OS and applications and any data you want to access "fast"
    2. Use an external USB HDD married with the internal 32GB as a Fusion Drive for data.
    In other words, accelerate the external USB HDD with the 32GB of SSD.

    Note: Use another drive for Time Machine, not the SSD+external-HDD Fusion Drive. Since your Fusion Drive will be partly external, it is easier for you to break it (i.e. knock the cable out for example) and you'll need to rely on a backup if the Fusion Drive doesn't come back up.
     
  20. Elembytes thread starter macrumors newbie

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    Jan 20, 2018
    #20
    How do I not allow High Sierra to attempt to put the APFS onto my iMac since it has the FUSION Drive? I thought at one point in time you had to make a choice or it allowed you to do so or something. That is why I have NOT updated to High Sierra because I didn't want to mess with my HFS. I was waiting until Apple finally addressed those of us with older iMacs with Fusion which finally they have in Mojave.
    If there is an easy way to NOT mess things up by upgrading to Sierra I will do it. Otherwise I'll have to wait until Fall to switch to Mojave. Thanks for your help!
     
  21. mj_ macrumors 6502

    mj_

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    #21
    I think you're mixing things up quite a bit here. Either that or I don't really understand what you're trying to say. APFS and High Sierra are not synonymous - High Sierra can easily run off of HFS+ partitions as well. And since APFS is only supported for SSDs in High Sierra the installer is never going to attempt to put APFS on your iMacs Fusion Drive simply because it isn't supported yet. This means that when attempting to install High Sierra on a Fusion Drive or regular hard disk drive the volume is NOT converted to APFS but remains formatted as HFS+ (Mac OS Extended (Journaled)). Case in point: my iMac with FD is running High Sierra on a regular HFS+ volume while my 12" MacBook is running High Sierra on an APFS volume.

    With Mojave, this is going to change. HFS+ is no longer supported in 10.14 at all, which means that EVERY SINGLE DRIVE - be that SSD, Fusion Drive, or HDD - is going to get converted to APFS whether you like it or not. And unlike in High Sierra the undocumented switch to prevent this from happening no longer seems to be working. Thus, there is no way to run 10.14 off an HFS+ drive.

    In other words: waiting for Mojave will get your drives converted to APFS for sure, and there doesn't seem to be a way to opt out. Installing High Sierra, on the other hand, is not going to f*** up your file system but leave everything as is.
     
  22. EugW macrumors 603

    EugW

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    Jun 18, 2017
    #22
    You can't install Mojave onto an HFS+ drive, but my understanding is that HFS+ is still a supported format for external data drives.
     
  23. mj_ macrumors 6502

    mj_

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    #23
    Yes, that's my understanding too. Thanks for clarifying, my comment was a bit misleading in this regard. The installer is only going to convert the system drive to APFS and leave all other partitions and disks untouched.

    macOS will continue to require HFS+ support until Apple's engineers either figure out a way to port Time Machine to APFS or replace it with something else. As we speak, a Time Machine backup drive needs to be HFS+ formatted.
     
  24. DotCom2 macrumors 68040

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    #24
    This is what I want to know. When I install Mojave and it automatically converts my Fusion Drive to APFS, what is going to happen to my 2 connected spinners using HFS+ ???
     
  25. mj_ macrumors 6502

    mj_

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    #25
    Nothing. Absolutely nothing. Zero. Nada.
     

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