We have learnt that when the macOS High Sierra arrives that all flash storage drives will be automatically converted to the new drive format system APFS, when you install High Sierra, you won't be able to opt-out of the transition to APFS.

In a support document aimed at system administrators, preparing for changes to APFS working in business or education sectors they explain that the Apple File System (APFS), will be the default file system in macOS High Sierra for Mac computers with all flash storage. 

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 won't be able to opt-out of the transition to APFS.

APFS Compatibility With macOS High Sierra

• Devices formatted as HFS+ can be read and written to by devices formatted as APFS.
• Devices formatted as APFS can be read and written to by:
  • Other APFS-formatted devices.
  • HFS+ formatted devices running macOS 10.12.6 or later.

For example, a USB device formatted as APFS can be read by a Mac running macOS High Sierra, but not by a Mac running OS X El Capitan or earlier.

APFS And FileVault

FileVault volumes are converted from HFS+ to APFS, just like unencrypted volumes. 

APFS And Boot Camp

Boot Camp is supported when upgrading to macOS High Sierra, unless the Boot Camp volume is greater than 3 TB and resides on a Fusion Drive. Boot Camp doesn't support Read/Write to APFS-formatted Mac volumes.

APFS And File Sharing

Volumes formatted with APFS can't offer share points over the network using AFP. SMB and NFS are supported when using APFS. The option to enforce only SMB-encrypted share points is also available.

APFS and Time Machine

After you upgrade your institution's Mac and convert to APFS, you won't need to make any changes to Time Machine settings. Any Time Machine share points must be shared over SMB instead of AFP.

Our Advice

Make sure you have a full backup BEFORE you start so if it all goes wrong you haven't lost everything on that drive.

You can learn more about the Apple File System in our article macOS High Sierra - What Is Under The Hood?