Top 5 questions about APFS and macOS High Sierra asked by Mac users

The new Apple File System (APFS) was one of the most important and exciting changes introduced in macOS High Sierra. 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.

Here at DaisyDisk team, we took APFS very seriously and spent a lot of time researching into the new file system. APFS is still quite scarcely documented, and many nuances could only be discovered by trial and error. We even had to reach out to Apple engineers for the most difficult bits.

And finally, we have implemented all our findings in DaisyDisk, releasing the new version 4.5 (free update for existing users).

Most questions people ask about APFS are in fact caused by the so called local snapshots of Time Machine.

Time Machine is a great backup utility built in macOS. Every hour or so it takes a snapshot of your entire disk and stores it locally, i.e. on the same disk. Later the snapshots are copied to an external permanent storage, such as NAS, and eventually deleted from the local disk.

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. So if you don’t make sizeable changes to your data, new local snapshots do not take additional disk space. But if you do make significant changes, such as when you delete a big file, the snapshot grows by the corresponding amount.

The space occupied by local snapshots is also called purgeable. When the snapshots grow too big or become older than 24 hours, or apps demand more space, macOS quickly deletes them and reclaims the purgeable space. The whole process is automatic, no user action is required.

However, sometimes the local snapshots become a problem and a source of questions for Mac users. Namely:

Question #1: Mysteriously disappearing disk space

Suppose you want to backup your iPhone to iTunes, or create a new disk image with Disk Utility, but suddenly you can’t, because the app reports insufficient free space on disk. This is confusing, because Finder on the other hand displays quite a lot of available space. This happens because Finder counts the local snapshots of Time Machine toward the available space, assuming that they can be reclaimed quickly upon demand. However if an app checks the amount of ACTUALLY free space, BEFORE the operation — which seems the case — then it fails, and you cannot proceed until you somehow remove the local snapshots.

Question #2: Deleting files doesn’t produce free space, or at least not immediately

You notice that despite you have deleted tens of GBs of files, the disk’s free space hasn’t grown at all. This happens because Time Machine moves your files to the local snapshots, so the space is not physically freed until the snapshots are deleted. This will eventually happen automatically, but what if you need the space NOW?

Question #3: System taking too much space on macOS High Sierra

Wondering what’s taking up your disk space, you open About This Mac > Storage and see that the yellow System segment appears unrealistically large — tens of GBs, or up to 80% of your disk. This is because on macOS High Sierra, this System segment is not only a catch-all category for the system files, but also includes the purgeable space, i.e. the local snapshots. This is neither obvious nor useful when you need to free up space.

Question #4: How can I remove local snapshots of Time Machine? And where they are located?

In certain circumstances you may need to forcedly remove the local snapshots of Time Machine, to make room for a more important operation. However, macOS doesn’t seem to provide an obvious way to do it. Unlike in previous macOS versions, the content of local snapshots in APFS is entirely unreachable to the user, even if you search with raised access permissions. The APFS snapshots are like dark matter on your disk — you know it’s there, but can’t see the files. The only way to view and delete the snapshots (beside DaisyDisk ;) is to use the tmutil command-line tool in Terminal.

Question #5: Why Apple had to make things so complicated?

Some people dislike the fact that APFS impudently takes control over their disk space, as if it knows better what the user needs. We’ve asked Apple engineers regarding this. They see the free disk space as a resource that is otherwise underused. Why, they ask, you’d want to have most of your disk stay empty most of the time and not utilized for something useful? With APFS and its instant snapshots, the free disk space can now be used for temporary backups, which adds a layer of safety for your data, almost free of charge, of course as long as it just works.

How DaisyDisk helps solve these problems

DaisyDisk scans your entire disk and builds a size-oriented map of your files and folders. It can reach even restricted and system folders by scanning with raised access permission. The remaining used space, if any, DaisyDisk displays as well, labeling it as hidden space. The latter is useful to detect dark matter on your disk, such as the local snapshots of Time Machine. Starting with the recently released version 4.5, DaisyDisk can additionally single out the purgeable space, i.e. the local snapshots, displayed under the hidden space. In addition, you can forcedly delete that purgeable space by a simple drag-and-drop, as you’d delete a regular file in DaisyDisk.

DaisyDisk 4.5 Officially Released

Now it’s official: the long awaited DaisyDisk 4.5 is finally out!

It’s an important update, that took us a long time to research and develop. The main new feature — the extended support of the new Apple File System (APFS) and addressing the top questions about macOS High Sierra and APFS that we have received.

Download the new version

What’s new:

  • Extended support of the new Apple File System (APFS) on macOS High Sierra, in particular:
  • You can now see the purgeable space — the disk space taken by the local snapshots of Time Machine and other caches, which cannot be scanned, but can now be identified inside the hidden space.
  • And you can now reclaim that purgeable space.
  • Added display of the free space in the right sidebar list, along with the estimation of available space, that is, free + purgeable.
  • Added display of the space taken by other volumes in the same APFS container, inside the hidden space.
  • Lots of bugs fixed.

Please upgrade by downloading the new version from our website, or by using Check for Updates… menu command from within the app.

The updated user manual can be found here.

DaisyDisk 4.5 Beta is now public, adds support of APFS and macOS High Sierra

DaisyDisk 4.5 beta has been released, please download here.

This update adds full support of APFS and macOS High Sierra.

Full change log here.

Your feedback and bug reports would be appreciated!

Today DaisyDisk turns 8!

8 years ago, on March 13, 2009, the very first copy of DaisyDisk v.1 was sold, so today can be called the official birthday of DaisyDisk!

It have been a really stunning 8 years. Four major version releases, three Apple’s Best of Mac App Store awards, recognition by industry’s media in over 450 reviews, lots of happy customers.

To celebrate this anniversary, the price suddenly goes down by 50% for 24 hours 😉🎂

DaisyDisk 4.4 fixes display of hidden space, adds Japanese language

DaisyDisk 4.4 both stand-alone and Mac App Store versions are now live.

A minor yet an important update.

We’ve finally addressed a small but annoying issue that has been plaguing the Mac App Store version of DaisyDisk for quite a while. Unlike its stand-alone counterpart, the App Store’s DaisyDisk lacked the display of hidden disk space, so in some cases our App Store customers were confused by the apparent mismatch between the sum of all scanned folders and the disk’s total used space. With the recent introduction of our free license migration service, we are finally able to display the full disk usage information in both DaisyDisk versions, and give all our users a meaningful path to reveal the hidden space, if they need to.

Also in this update we’ve improved the order, in which the disks and volumes are displayed in the overview of disks. Partitions are now sorted alphabetically by their names, grouped by physical disk were they are located. (Previously, all partitions were sorted by their logical names.) Network shares are grouped by their corresponding remote servers.

And finally, we’ve re-added the Japanese language! 🇯🇵

Full change log here.

DaisyDisk 4.3 adds Spanish and Chinese languages, fixes bugs

DaisyDisk 4.3 both stand-alone and Mac App Store versions are now live.

In this update we re-added Spanish and Chinese localizations (both Simplified and Traditional) and fixed a few bugs. Full change log here.

DaisyDisk 4.2 adds Polish language, fixes bugs

DaisyDisk 4.2 both stand-alone and Mac App Store versions are now live.

In this update we re-added Polish localization and fixed a bug that caused timeouts on network disks. Full change log here.

DaisyDisk 4.1.1 adds French and Swedish languages

DaisyDisk 4.1.1 both stand-alone and Mac App Store versions are now live. Update! :)

In this update we re-added French and Swedish localizations. Full change log here.

DaisyDisk 4.0.3 fixes the Sparkle vulnerability, adds German and Russian languages

DaisyDisk 4.0.3 stand-alone version is now live, the Mac App Store version is submitted for review and is coming soon.

Update! :)

This update fixes the recently revealed Sparkle vulnerability, though at the time we were already using HTTPS so DaisyDisk users were not likely affected. Beside th fix, we re-added German and Russian localizations. Full change log here.

Please note that if you are using stand-alone DaisyDisk 4.0.1 on El Capitan, you’ll have to update manually, that is, by downloading and replacing the app. The built-in updater was unfortunately broken in DaisyDisk 4.0.1. It should still work fine though on OS X Yosemite.

Apple’s Best of 2015

Apple has unveiled its Best of 2015 collection in the Mac App Store:

What you see here made the cut—they’re the most visionary, inventive, and irresistible apps and games of the year.

And guess what, DaisyDisk is one of them, yay! :)

And this is our third time. DaisyDisk 3 was in Best of 2013; and DaisyDisk 2 was in Best of 2011. In fact, all our major updates were named.

Stay tuned.