Why is there a volume on the iMac called “VM” when I don’t use a virtual machine

macosstorage

It's in Macintosh>System>Volumes.
Screenshot of the finder window containing said volume

screenshot of the finder window containing said volume(s)

Best Answer

VM in this case isn't Virtual Machine, it's Virtual Memory - swap space.

Because volumes on APFS disks have no fixed boundaries they can be instantly resized without penalty. This allows the swap space to be actively shrunk or expanded to suit the current requirements without any delay in processing, unlike on HFS+ or NTFS.

Keeping it as 'a volume' rather than 'a file' is just tidy housekeeping. It allows items to be added, overwritten or deleted without needing to keep monolithic integrity as with a pagefile-type structure.

The Mac tends to hide a lot of this from the user, so they don't try to mount it or access it like any other volume. It's best left alone, let the System manage it.

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