Mike Bombich, creator of Carbon Copy Cloner:
This week we reported to Apple a serious flaw in macOS that can lead to data loss when using an APFS-formatted disk image. Until Apple issues a macOS update that resolves this problem, we’re dropping support for APFS-formatted disk images.
Note: What I describe below applies to APFS disk images only — ordinary APFS volumes (e.g. your SSD startup disk) are not affected by this problem. While the underlying problem here is very serious, this is not likely to be a widespread problem, and will be most applicable to a small subset of backups. Disk images are not used for most backup task activity, they are generally only applicable when making backups to network volumes. If you make backups to network volumes, read on to learn more.
Another day, another serious High Sierra bug.
Apple File System (APFS), is the default file system in macOS High Sierra for Mac computers with all flash storage. APFS features strong encryption, space sharing, snapshots, fast directory sizing, and improved file system fundamentals.
When you upgrade to macOS High Sierra, systems with all flash storage configurations are converted automatically. Systems with hard disk drives (HDD) and Fusion drives won’t be converted to APFS. You can’t opt-out of the transition to APFS.
Please make sure to create a good backup (or three!) before upgrading to High Sierra, because Shit Happens™ when you don’t have one (or three!).
HFS+ and it’s predecessor HFS are more than 30 years old. These file systems were developed in an era of floppy disks and spinning hard drives, where file sizes were calculated in kilobytes or megabytes. Today, solid-state drives store millions of files, accounting for gigabytes or terabytes of data. There is now also a greater importance placed on keeping sensitive information secure and safe from prying eyes.
A new file system is needed to meet the current needs of Apple products, and support new technologies for decades to come.
I can only imagine John Siracusa’s grin, smile or tension-releasing-sigh when he first heard of this news.