APFS creates VM disk?

LK LAW

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Original poster
May 30, 2016
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What is the purpose of this?
Screen Shot 2017-06-30 at 11.31.05.png
[doublepost=1498815412][/doublepost]Any idea what the PreBoot partition is for?
Screen Shot 2017-06-30 at 11.35.23.png
 

Ritsuka

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Sep 3, 2006
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APFS can share space between partitions. So there is no downside in making a stand alone VM partition.
 

LK LAW

macrumors regular
Original poster
May 30, 2016
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APFS can share space between partitions. So there is no downside in making a stand alone VM partition.
No but what are these partitions used for? And how does it defer from what HFS used to be?
 

Ritsuka

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Sep 3, 2006
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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.
 

LK LAW

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Original poster
May 30, 2016
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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.
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?
 

aldrinjtauro

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Jul 3, 2014
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Birmingham, AL
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?
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.
 
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msephton

macrumors 6502
Jan 6, 2004
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Cornwall, UK
I answered a similar question in Apple Developer Forums. In a Terminal window:

diskutil apfs updatePreboot
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.