APFS creates VM disk?

Discussion in 'macOS High Sierra (10.13)' started by LK LAW, Jun 30, 2017.

  1. LK LAW macrumors member

    Joined:
    May 30, 2016
    #1
    What is the purpose of this?
    Screen Shot 2017-06-30 at 11.31.05.png
    --- Post Merged, Jun 30, 2017 ---
    Any idea what the PreBoot partition is for?
    Screen Shot 2017-06-30 at 11.35.23.png
     
  2. Ritsuka macrumors 6502a

    Joined:
    Sep 3, 2006
    #2
    APFS can share space between partitions. So there is no downside in making a stand alone VM partition.
     
  3. LK LAW thread starter macrumors member

    Joined:
    May 30, 2016
    #3
    No but what are these partitions used for? And how does it defer from what HFS used to be?
     
  4. Ritsuka macrumors 6502a

    Joined:
    Sep 3, 2006
    #4
    VM is for the swap. If your apps requires more RAM than the one you have it will use the space in the VM partition. HFS+ had one or more swap file instead.
     
  5. LK LAW thread starter macrumors member

    Joined:
    May 30, 2016
    #5
    Didn’t Ubuntu Just ditch the swap ditch the swap partition instead in favor of swap files?

    Also got any idea what the preboot partition does?
     
  6. aldrinjtauro macrumors regular

    Joined:
    Jul 3, 2014
    Location:
    Birmingham, AL
    #6
    Well, I don't think Ubuntu's system would work the way APFS does with volume space sharing. I think an Ubuntu swap partition would remove that space from availability irreversibly.

    No idea what pre-boot is.
     
  7. grahamperrin macrumors 601

    grahamperrin

    Joined:
    Jun 8, 2007
    #7
    The same with APFS. Swap files.

    I answered a similar question in Apple Developer Forums. In a Terminal window:

    diskutil apfs updatePreboot
     
  8. msephton macrumors 6502

    msephton

    Joined:
    Jan 6, 2004
    Location:
    Cornwall, UK
    #8
    That doesn't answer what the reboot partition does. Rather it shows one thing you can do to it.

    As I understand it, the reboot partition does some pre-boot housekeeping and security tasks, then hands off to the main boot partition.
     
  9. cmaier macrumors G3

    Joined:
    Jul 25, 2007
    Location:
    California
  10. grahamperrin macrumors 601

    grahamperrin

    Joined:
    Jun 8, 2007
    #10
    Apple should update its developer document, The Early Boot Process
     

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