There are substantial differences in the structure of the internal disks in macOS, iPadOS and iOS, as shown here. And there are at least 24 cryptexes now used to support AI.
APFS
Should you run First Aid on your Data volume before updating macOS, or as routine housekeeping? And how should you run it?
Distinguishing conventional copies, clone files, symlinks, hard links and Finder aliases can be confusing. Here’s how to tell them apart with using Terminal.
Read-write and VM disk images are created and maintained differently, but they can both be APFS sparse files. Explanation of their creation and maintenance.
From early code pages based on language-specific variants of Extended ASCII, through 2-byte support in WorldScript II, to Unicode and the annual emoji update.
A brief start with MFS for 400 KB floppies, followed by HFS intended for the first hard disks, upgraded to HFS+ in 1988, and followed in 2017 by APFS for all the OSes.
How read-write disk images and those used in Apple silicon virtual machines use sparse file format to save space on disk.
How do clone files and sparse files cope with being backed up and restored? Can they save space in iCloud Drive? Some of these answers may surprise.
Deleting clone files saves no space, but converting copies into clones could free up plenty of storage. Sparse files can also be highly efficient, and squeeze 285 GB into just 16.5 GB.
Systematic and thorough account of the structure and function of bootable external disks and dual-boot systems from High Sierra to Sequoia, and how to diagnose their problems.
The Eclectic Light Company 