Among the many announcements at Apple's WWDC event yesterday, the company also announced that it will be replacing the aging HFS+ file system with Apple File System (APFS), coming as a preview now with an eventual wide release in 2017. The new file system is now available as a technical preview with the developer preview of macOS 10.12 Sierra.
Apple hails the new system as "a new, modern file system for iOS, OS X, tvOS and watchOS. It is optimized for Flash/SSD storage and features strong encryption, copy-on-write metadata, space sharing, cloning for files and directories, snapshots, fast directory sizing, atomic safe-save primitives, and improved file system fundamentals."
However, the preview does come with some documented limitations, with the following not available for use within it:
- Startup Disk: APFS volumes cannot currently be used as a startup disk.
- Case Sensitivity: Filenames are currently case-sensitive only.
- Time Machine: Time Machine backups are not currently supported.
- FileVault: APFS volumes cannot currently be encrypted using FileVault.
- Fusion Drive: Fusion Drives cannot currently use APFS.
In terms of encryption capabilities for the new system, Apple says:
"APFS supports encryption natively. You can choose one of the following encryption models for each volume in a container: no encryption, single-key encryption, or multi-key encryption with per-file keys for file data and a separate key for sensitive metadata. APFS encryption uses AES-XTS or AES-CBC, depending on hardware. Multi-key encryption ensures the integrity of user data even when its physical security is compromised."
More information on APFS can be found in the official documentation here. APFS will ship as a technical preview along with macOS Sierra later this year, and is expected to replace HFS+ fully sometime in 2017. For more information on the developer preview of macOS 10.12 and download instructions, go here.