Update adds two new datestamp fields, and gives decimal seconds in times. Use this app to explore how macOS sets those on files, as shown.
APFS
What can cause low copy speeds for very large and possibly sparse files, such as VMs? Causes explained, and tools you can use to discover why.
Most backup apps make snapshots, so why not use those instead of conventional backups? Because of the weaknesses of snapshots, as explained.
Originally two separate apps, they were brought together in Mac OS X, and have survived largely unscathed to Sequoia. Here are some highs and lows to remember.
Sparse files are now common among databases, disk images, and virtual machines. How they work in APFS, how they’re created, and how they can explode.
Consider the fidelity of backup copies, the speed of a backup method, and the risk of losing the contents of that backup. And test backups by restoring samples from them.
Classic TM backed up HFS+ to HFS+; current TM backs up APFS to APFS. But what if you want to back up a mixture of APFS and HFS+ volumes?
How the resource forks of Classic Mac OS became extended attributes in Mac OS X 10.4, then flourished. How clone files handle xattrs, and which are used by APFS itself.
If the Finder’s Get Info dialog may report inaccurate total file size, does that mean the folder sizes are also incorrect? And does this affect volumes too?
How to obtain and read entries in the Unified log made by APFS. Their structure, and a guide to their identification and occurrence.
The Eclectic Light Company 