OS X High Sierra: Apple’s new desktop file system APFS

With the release of OS X 10.13 High Sierra, Apple is bringing its proprietary ‘Apple File System’ (APFS) - already found on Apple mobile devices - to the Mac platform.  In this primer we’ll take a look at some of the advantages of the new file system, how to migrate to it, and what the potential pitfalls are with making the switch.

Advantages of APFS

One of the biggest benefits to come with APFS is improved performance with certain file operations. You may notice faster directory sizing (when using ‘Get Info’ on a folder) and faster copy speeds when duplicating files. APFS also is more resistant to data corruption and loss of data integrity, due to the way it handles read and write operations.

Finally, APFS is much more flexible when it comes to configuring multiple logical volumes on a single physical disk. In older file systems, a user would need to allocate space in advance, creating partitions of a static size. If the partitions became full, the volumes would need to be manually resized. With APFS’ space-sharing, the file system automatically resizes logical volumes to allow for more capacity (so long as there is space available on the disk itself).

How Do I Migrate?

Migration to APFS is automatic when you upgrade your system to OS X 10.13, assuming your drive is an SSD or flash drive.  It is important to note that Apple enforces this conversion - there is no opting out while migrating to High Sierra. Fusion drives and traditional hard drives will not be converted.

This conversion will only affect your primary system drive. Any attached external storage will retain whatever file system it previously held.  This is a good thing, as it will allow the device to remain compatible with either Windows-based systems or older Macs that are not running APFS.  Any existing Time Machine drives will also remain on the older HFS+ file system. This is fine - do not try to convert your Time Machine drive manually!

Pitfalls with APFS

As with any major shift in OS infrastructure, the migration to APFS poses its own share of compatibility issues and migration headaches that Apple will iron out over future releases and patches.  While APFS is the way of the future, it may be necessary for your site to downgrade any newly-shipped Macs running High Sierra back to HFS+ for the time being.

The new file system does not play nicely with Boot Camp. A Windows system running alongside a High Sierra install will not yet be able to read APFS, even with Boot Camp installed.  It is still possible to boot into either OS, but you will need to hold down the Option key while the system is starting in order to reveal all available startup disks. While not a major issue, it’s a point to consider if your site uses systems running Boot Camp.  It’s likely Apple will provide a fix for this in an upcoming release.


Overall, indications are that APFS will bring additional stability and reliability to everyday file operations, leading to less data degradation and better system performance.  The introduction of space sharing allows for greater flexibility in configuring multiple logical volumes. While many of these changes are under the hood, they should lead to a better overall experience when copying, saving, and preserving your data.

APFS isn’t going anywhere, potential compatibility headaches aside - Apple has been using it on its mobile and smart devices for the past few years now and it was inevitable that they’d introduce it to their OS X platforms.  As always, compatibility issues will be resolved with future service pack releases both from Apple and developers like Autodesk and Adobe, allowing for smoother conversion to the new file system while using pro software. Nodal will be keeping an eye on this new technology in the months ahead.

For more information on APFS, HowToGeek has you covered.  We’re happy to answer any questions you might have, just drop us a line.