An APFS crash can cause data loss in macOS High Sierra when writing to disk images

Apple introduced the APFS disk format with the introduction of macOS High Sierra. Only Macs that have the latest Apple operating system and their disk system is an SSD disk, have been able to change the disk format. Therefore, Fusion Drive systems and Macs with mechanical drives were excluded.

All new system must be refined, but in principle all were advantages. One of the disadvantages is the one that has been made known Mike bombich, creator of the well-known backup program Carbon Copy Cloner. You have discovered a data write failure on disk images with APFS.

The specific data can be found on Bombich's own blog. We users who have macOS High Sierra and we see that our file system is APFS should not be worried. Actually, this failure affects very specific processes. An average user does not have to write to disk images. Recall that a disk image is a file that mounts to the desktop and acts as an external drive connected to the Mac. Mr. Bombich describes the finding as follows:

Earlier this week I noticed that an APFS-formatted sparsebundle disk image volume was showing ample free space, even though the underlying disk was completely full. I copied a video file to the disk image volume to see what would happen. It was copied without any error! I opened the file, verified that the video played to the end. I checked the file, from what I could see, the file was intact and complete on the disk image. However, when I unmounted and remounted the disk image, the video was corrupted. If you've ever lost data, you know the kick in the stomach feeling. Luckily I was just running some tests and the missing file was just test data.

Those who can face the problem are specific users. Mainly occurs when backing up network volumes. At the moment Cabon Copy Cloner has deactivated the option to copy these files that are scattered, warning of this. Apple is expected to modify the system in future updates.