The space occupied by local snapshots is also called “purgeable”.

But if you do make significant changes, such as when you delete a big file, the snapshot grows by the corresponding amount. So if you don’t make sizeable changes to your data, new local snapshots do not take additional disk space. Note that unlike the external backup, local snapshot is not an actual copy of data, but rather a catalog of changes since the last snapshot. Later the snapshots are copied to an external permanent storage, such as NAS, and eventually deleted from the local disk. Every hour or so it takes a “snapshot” of your entire disk and stores it locally, i.e. Time Machine is a great backup utility built in macOS. Most questions people ask about APFS are in fact caused by the so called “local snapshots of Time Machine”. We even had to reach out to Apple engineers for the most difficult bits.Īnd finally, we have implemented all our findings in DaisyDisk, releasing the new version 4.5 (free update for existing users).

APFS is still quite scarcely documented, and many nuances could only be discovered by trial and error. Here at DaisyDisk team, we took APFS very seriously and spent a lot of time researching into the new file system. However, with all its new power, APFS also brought a number of new questions for Mac users, which we see asked in numerous online forums and in support tickets that we receive. The new Apple File System (APFS) was one of the most important and exciting changes introduced in macOS High Sierra. Blog Mar 28, 2018 Top 5 questions about APFS and macOS High Sierra asked by Mac users

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