How the immutable system of the SSV, the firmlinked Data volume, and cryptexes ‘grafted’ into the directory tree combine to form the boot volume group of Intel and Apple silicon Macs running macOS 15.
firmlink
Overview of clone files, dataless files, sparse files, symbolic links, and firmlinks, and how used and free space is accounted for in APFS.
Without firmlinks, the System and Data volumes couldn’t have been separated, and Secure Boot couldn’t have worked.
Updated charts of containers and volumes on boot volume groups for Ventura, with details of cryptexes and what they do.
Which should you use, and what are their strengths and drawbacks? Symbolic links, hard links, aliases and bookmarks explained – oh, and a mention of firmlinks too.
Detailed account of disk, volume and folder layouts on Big Sur’s boot disks, complete with roadmaps which are downloadable as PDFs.
Diagrams of the layout of volumes on boot disks for macOS 10.13 to 11, covering both Intel and M1 models.
A complete guide to the structure and layout of APFS startup disks from High Sierra to Big Sur (Intel), together with tear-out PDF charts.
macOS Catalina is the first version of macOS which boots not from a single volume, but from two: […]
The third successive macOS upgrade brings fundamental changes which could so easily have resulted in catastrophe. How did Apple pull it off?
The Eclectic Light Company 