Understand how TM backs up and how snapshots work to minimise the size of local snapshots and backups, and the time they take. How to ensure files in iCloud Drive are backed up properly.
snapshot
When do sparse files explode to full size, and how could you preserve them in transit? Can you copy clones or snapshots? How to preserve extended attributes?
Most backup apps make snapshots, so why not use those instead of conventional backups? Because of the weaknesses of snapshots, as explained.
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 to obtain and read entries in the Unified log made by APFS. Their structure, and a guide to their identification and occurrence.
What’s in an APFS snapshot, and how the stages in its life-cycle work, from creation, through mounting and unmounting, to deletion and cleanup.
Introduced in iOS 10.3 on 27 March 2017, then in macOS 10.13 six months later. It ups and downs, and where it still has further to go.
Understanding how APFS works: inodes, attributes, file extents, extended attributes, and how they change with editing and cloning.
How are snapshots made, and what do they contain? How are they sized, and can they grow? How can you copy a snapshot, or remove a file from one?
When did you last see figures on your Mac that were unbelievable, like 60 TB of snapshots on a 2 TB SSD? We need more sanity checking.
The Eclectic Light Company 