Union mounts let you merge the contents of two volumes without copying any files. Do they work as expected in Sonoma’s APFS, though?
file system
Other file systems, with an outline of vfs and vnodes used by the kernel, and how they’re important in checking code signatures.
B+trees, directory records, directory and file names and Unicode normalisation, and whatever happened to the promise of fast directory sizing?
Two problems undermine Disk Utility’s First Aid: it persisting bug in failing to unmount volumes to check and repair, and its default omission of containers. And errors in APFS seem to be on the rise.
What’s in APFS, and what are its tools? How to interpret the version number, and what do we know has changed with different versions? How compatible are they?
Details of what happens when an APFS (Encrypted) volume is mounted, when mounting a Time Machine snapshot, unmounting a volume, and loading a Cryptex.
Enabling the TRIM command was once thought important to maintain good write performance on SSDs. What has happened to it? Should we still be enabling it?
How APFS can trim free space in a read/write disk image and transform it into a sparse file, so it uses storage more efficiently.
How APFS containers and volumes work. What hard links, clones and sparse files are, and when they break down.
ResEdit changed what was in the resource fork. With Mac OS X, Apple moved away from forks to extended attributes, now used for quarantine flags and more.
The Eclectic Light Company 