Snow Leopard in Parallels 15 under High Sierra on an APFS SSD?

Discussion in 'Mac OS X Guest OS Discussion' started by NigelJ1, Apr 22, 2020.

  1. NigelJ1

    NigelJ1 Bit Poster

    Hi all,
    I'm currently running Snow Leopard inside Parallels under Mac OS 10.12 Sierra on a Mid 2010 Mac Pro. It runs very nicely too.
    However, I have been considering upgrading the Mac OS to 10.13 High Sierra, and my question is as follows:
    My start-up drive is an SSD, and I understand that installing High Sierra on an SSD drive will convert the drive format to APFS.
    I have also read that Apple's APFS format is not backwards compatible with operating systems prior to High Sierra.
    Does it therefore necessarily follow that Snow Leopard will no longer run on this drive, even as a VM within Parallels 15, once the drive been formatted as APFS?
    Thanks and regards.
  2. NigelJ1

    NigelJ1 Bit Poster

  3. HannesR

    HannesR Bit Poster

    I have just done a similar migration - upgrading my 2010 Mac Pro from Sierra to High Sierra. In my case, the virtualized macOS is Mavericks, but this should not make a difference. The VM runs without any problems, and although the SSD of the host system is formatted in APFS the "Macintosh HD" within Mavericks stick reports as "MacOS Extended (Journaled)". The container managed by Parallels does the trick - when virtualizing Windows it also hosts NTFS without a problem.

    BTW, on my MacBook Pro I made the step from Mojave to Catalina, and a copy of the very same VM runs there smoothly as well.
  4. NigelJ1

    NigelJ1 Bit Poster

    Many thanks for the info HannesR, that's really interesting.

    I guess it should have occurred to me that since Windows still runs happily as a guest OS under High Sierra and later (i.e. host systems that, if installed onto SSDs, are likely to be using APFS in the vast majority of cases), those Windows installations must be residing on a virtual HD that is clearly not APFS.

    I wonder how this actually works. In the past, when installing an OS onto a Mac/PC in the traditional way, the HD has always had to be appropriately formatted before running an OS installer. For example, in the case of a Windows installation into Parallels, how does Parallels know it needs to provide an NTFS-formatted virtual HD, and where do the resources come from to allow this to happen?

    Does Parallels recognise the OS being installed into it, and format the virtual HD accordingly from its own resources?
    Or does it somehow initiate the formatting using the drive formatting utility built into the guest OS installer package (e.g. does it access and run Disk Utility when installing a guest Mac OS)?

    I'm not a programmer, but I find this fascinating and I'd love to know how Parallels actually facilitates the provision of an appropriate drive format for the virtual HD on an OS by OS basis.
  5. iosm

    iosm Bit Poster

    Another issue I have noticed is if I switch an app to Coherence view, there is no menu bar! This makes a lot of apps unusable as critical actions are accessed from the menu bar. thanks

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